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Multiwfn Version 3.7 (Release date: 2020-Aug-14)

NEW FUNCTIONS
• Functionality of quantitative molecular surface analysis module (main function 12) has been extended. A new option "14 Calculate area of the region around a specific surface extreme" is added to post-process menu, this is very useful for measuring local surface area (i.e. size) of sigma-hole or pi-hole. See corresponding introduction in Section 3.15.2.2 of manual and practical analysis example in Section 4.12.10. In addition, a new option "15 Basin-like partition of surface and calculate areas" is added, it is useful for unveiling how the whole molecular surface is composed of individual surface basins corresponding to various surface ESP extrema, see study example in Section 4.12.11.
• Exporting loaded or calculated grid data to .vti file is supported by subfunction 2 of main function 100. .vti can be visualized by the very powerful volumetric data visualizer ParaView (freely available at https://www.paraview.org). This function now also supports exporting current structure to .cml file, which can be loaded by ParaView to show molecules.
• Subfunction 17 is added to main function 200, it is used to calculate Coulomb and exchange integral between two orbitals based on uniform grid, see Section 3.200.17 of manual for detail and example. In the future version, evaluating these integrals via analytical method may be also available (in that case the cost will be significantly lower).
• Subfunction 6 of main function 200 now is also able to calculate overlap integral between norm of orbitals of two sets of wavefunctions, this quantity is useful for measuring orbital superposition. See Section 3.200.6 of manual for detail.
• Many data related to Hyper-Rayleigh scattering (HRS) now can be computed via subfunction 7 of main function 200. See Section 3.200.7 of manual for introduction and 4.200.7 for example.
• [2019-Aug-9] Density difference now can be decomposed to orbital contributions. For example, one can use this function to study which NBO orbital(s) have evident contribution to Fukui function. See Section 3.200.13 of manual for introduction and Section 4.200.13 for example.
• [2019-Aug-11] Bond length alternation (BLA), bond order laternation (BOA), bond angle and dihedral alterations for a given chain now can be very easily calculated via subfunction 18 of main function 200. This function is particularly useful for studying conjugated oligomers or conjugated paths. See Section 3.200.18 of manual for introduction and 4.200.18 for example.
• [2019-Aug-20] The procedure of calculating kinetic diameter for small molecules using the method proposed in J. Phys. Chem. A, 118, 1150 (2014) has been illustrated in Section 4.12.12 of manual.
• [2019-Sep-7] Two-level and three-level analyses of first hyperpolarizability have been supported in sum-over-states (SOS) module of Multiwfn. See Section 3.200.8.2 for detail and Section 4.200.8.2 for example.
• [2019-Sep-11] Multiwfn now is able to parse second polarizability from "polar" task of Gaussian and print it in readible format and give relevant information. See updated Section 3.200.7 for introduction and Section 4.200.7 for example.
• [2019-Sep-27] When plotting spectra via main function 11, user can use new option 23 to add spikes at bottom of the spectrum to clearly indicate position of transition energies, different colors can be used to highlight different types of transitions, the height can be used to reflect degree of degenerate. See example in Section 4.11.9 for illustration.
• [2019-Sep-27] An option "Tools - Batch plotting orbitals" is added to menu bar of main function 0. This option can very conveniently save isosurface graphs for a batch of given orbitals.
• [2019-Sep-27] A special form of PDOS, namely "MO-PDOS" now can be plotted by main function 10. MO-PDOS map can clearly reveal contribution to DOS from different sets of MOs. See Section 4.10.5 for introduction and example.
• [2019-Oct-11] Subfunction 2 of main function 100 now can export .mkl file (old Molekel input file). This is particularly useful for ORCA users if they want to use wavefunction generated by other quantum chemistry codes as initial guess of ORCA, namely using other codes to generate .fch or .molden file first, then use Multiwfn to convert it to .mkl, and finally use orca_2mkl test -gbw to convert test.mkl to test.gbw.
• [2019-Oct-13] The real space function generated by 3D cubic spline interpolation based on the grid data in memory is supported as user-defined function with index of -3. This function is more smoother and usually more accurate than the function evaluated by trilinear interpolation (user-defined function -1) when grid spacing is relatively large.
• [2019-Oct-14] In the spectrum plotting function (main function 11), minima and maxima of spectrum can be directly labelled on the spectrum, see updated Section 4.11.3 on how to do this. Exact values of spectrum extrema are now directly printed on screen when choosing option 0 to plot map; the use of option 16 has been completely changed, now it is used to set how to show extreme labels.
• [2019-Oct-15] A new molecular descriptor "Molecular polarity index" (MPI) as well as polar and nonpolar surface areas are automatically outputted after performing quantitative molecular surface analysis for electrostatic potential via main function 12. See Section 3.15.1 for introduction of its definition. The larger the MPI, the higher the molecular polarity.
• [2019-Oct-19] The RESP fitting module now supports generate equivalent constraint file based on point group symmetry of local regions or the entire system, see "Example 5" of Section 4.7.7 for illustration. This feature is particularly useful and convenient if you want to make resulting charges satisfy molecular global or local symmetry.
• [2019-Oct-27] The AV1245 proposed in Phys. Chem. Chem. Phys., 18, 11839 (2016) has been supported as subfunction 11 of main function 9. This index is very useful in quantifying aromaticity of large ring (such as porphyrin). See Section 3.11.10 for introduction and 4.9.11 for example.
• [2019-Nov-16] In the AdNDP module, option 15 is added, which is used to compute orbital composition based on natural atomic orbitals (NAOs) for picked AdNDP orbitals.
• [2019-Nov-19] PEOE is a popular and very fast method of evaluating atomic charges, it has been supported as subfunction 19 of main function 7. This kind of charge is also known as Gasteiger charge. See Section 3.9.17 for introduction and Section 4.7.9 for example.
• [2019-Dec-21] Orbital delocalization index (ODI) is supported to quantify extent of spatial delocalization of orbitals on the whole system or on specific fragment. See Section 4.8.5 for example.
• [2020-Jan-5] Hole delocalization index (HDI) and electron delocalization index (EDI) have been supported in hole-electron analysis module, they are pretty useful in quantifying breadth of spatial distribution of hole and electron. See "Theory 3" of Section 3.21.1.1 for introduction and updated Section 4.18.1 for example.
• [2020-Jan-24] Adding additional fitting center is supported by RESP charge calculation module. See Example 6 of Section 4.7.7 for illustrative application.
• [2019-Jan-27] GUI (option 0) of basin analysis module now supports drawing basins within in rho=0.001 surface (via "Set basin drawing method" - "rho>0.001 region only" option in the menu bar). See updated Section 4.17 of manual for illustration. In addition, this video tutorial is highly suggested to have a look: "Drawing AIM basins (atomic basins) in Multiwfn and VMD" (https://youtu.be/9D5do80XcbI)
• [2019-Jan-28] Subfunction 15 is added to main function 18. It is used to show major MO transitions for all excited states, so that you can quickly recognize basic characteristics of various excited states in terms of MOs
• [2019-Jan-30] The RESP2 charge proposed in DOI: 10.26434/chemrxiv.10072799.v1 now can be easily calculated, see Section 4.7.7.9 for example. RESP2 is very suitable for molecular dynamics purpose.
• [2020-Feb-9] Van der Waals potential and its two components (repulsion potential and dispersion potential) now can be visualized via subfunction 6 of main function 20. See Section 3.23.7 for introduction and Section 4.20.6 for example. This analysis method has been published in DOI: 10.26434/chemrxiv.12148572.v1
• [2020-Feb-13] Bond order density (BOD) and natural adaptive orbital (NAdO) analyses proposed in J. Phys. Chem. A, 124, 339 (2020) has been supported. This is a useful method that can visualize contribution to delocalization index from various spatial regions. See Section 3.200.20 for introduction and 4.200.20 for example.
• [2020-Feb-23] Orbital-weighted Fukui function and orbital-weighted dual descriptor not can be easily calculated, see Section 3.100.16.3 of manual for introduction and 4.100.16.2 for illustrative application. Compared to standard form of Fukui function and dual descriptor, they are able to reasonably applied to systems with (quasi-)degenerate frontier molecular orbitals, such as C₆₀, coronene and cyclo[18]carbon.
• [2020-Mar-5] Pores or free regions in a box (usually simulated by molecular dynamics) can be visualized by subfunction 1 of main function 300, volume of free regions can also be calculated. See Section 3.300.1 for introduction and 4.300.1 for example.
• [2020-Mar-10] Sphericalized atomic radial density now can be easily fitted as multiple Slater type orbitals (STOs) or Gaussian type functions (GTFs) by subfunction 2 of main function 300. This module is quite robust and flexible. See Section 3.300.2 for introduction and Section 4.300.2 for practical examples.
• [2020-Mar-13] The ωcubic electrophilicity index introduced in J. Phys. Chem. A, 124, 2090 (2020) now can be automatically calculated by subfunction 16 of main function 100, see Section 3.100.16 for detail. It is shown that condensed form of this index at halogen atom in halogen bond dimers has ideal linear relationship with binding energy.
• [2020-Apr-3] The high ELF localization domain population and volume (HELP and HELV) defined in ChemPhysChem, 14, 3714 (2013) now can be calculated via basin analysis module. They can be used to study molecular properties that closely related to lone pair electrons. See the ChemPhysChem paper for detailed introduction and Section 4.17.8 of manual for illustration.
• [2020-Apr-10] The unit sphere representation and vector representation of (hyper)polarizability proposed in J. Comput. Chem., 32, 1128 (2011) has been supported as subfunction 3 of main function 300. They are quite useful methods of visualizing (hyper)polarizability tensor, see Section 3.300.3 of manual for introduction and 4.300.3 for example.
• [2020-Apr-19] The intrinsic bond strength index (IBSI) proposed in J. Phys. Chem. A, 124, 1850 (2020) has been supported. It was defined in the framework of IGM and demonstrated to be useful in characterizing strength for chemical bonds. See Section 3.11.9 for introduction and Section 4.9.6 for example.
• [2020-Apr-19] The IGM under Hirshfeld partition of actual molecular density (IGMH) proposed by Tian Lu has been supported as subfunction 11 of main function 20. This new form of IGM purely relies on wavefunction to perform IGM analysis, the result is more physically meaningful and graphical effect is better, though the cost is higher than the original form of IGM, which employs promolecular approximation. See Section 3.23.6 for introduction of IGMH and Section 4.20.11 for example.
• [2020-Apr-26] Scanning tunneling microscope (STM) image now can be well simulated by subfunction 3 of main function 300 of Multiwfn. Both constant height and constant current modes are supported, very nice image can be directly generated. See Section 3.300.4 of manual for introduction and 4.300.4 for example.
• [2020-Apr-26] IBSIW (intrinsic bond strength index for weak interactions) now can be calculated by option 6 of IGM and IGMH analysis modules. See Section 3.23.5 for introduction.
• [2020-May-31] AVmin index proposed in J. Phys. Chem. C, 121, 27118 (2017) has been supported for measuring aromaticity of large ring. See Section 3.11.10 of manual for detail.
• [2020-Jun-3] Orbital composition now can be computed based on AIM partition by newly added subfunction 11 of main function 17. This function can also computes composition contributed by various kinds of basins, such as ELF basin and Fukui function basin. See Section 4.8.6 for example.
• [2020-Jun-18] Molecular quadrupole and octopole moments now can be calculated via subfunction 2 of fuzzy atomic space analysis module. In addition, by defining fragment using option -5 in this module and then choose subfunction 2, you can calculate fragment dipole/quadrupole/octopole moments, see Section 4.15.3 for example of calculating fragment dipole moment.
• [2020-Jun-27] Electric dipole, quadrupole and octopole moments of present system now can be evaluated analytically by subfunction 5 of main function 300, see Section 3.300.5 of manual for introduction and 4.300.5 for example.
• [2020-Jul-3] The interaction region indicator (IRI) proposed by Tian Lu has been supported as subfunction 4 of main function 20. IRI is a function that able to equally well reveal chemical bond regions and weak interaction regions. See Sections 3.23.8 and 4.20.4 of manual for introduction and example, respectively. IRI is defined in a much simpler way than DORI, while graphical effect is found to be evidently better than DORI.
• [2020-Jul-26] Plotting NMR has been supported in main function 11. Output file of NMR task of Gaussian and ORCA are supported. See Section 3.13.5 of manual for detail and 4.11.10 for example.

IMPROVEMENTS AND CHANGES
• In the menu bar of main function 0, "Measure geometry" is added, by which you can easily measure distance, angle and dihedral between selected atoms.
• Option -2 of AdNDP module has been modified. Now it consists of a few suboptions, via "Set maximum number of candidate orbitals to be printed", one can customize the maximum number of candidate orbitals printed on screen during AdNDP searching.
• The way of plotting electrostatic potential colored vdW surface via script under Linux platform has been described in part 9 of Section 4.A.13.
• The interface for generating ORCA input file (option 12 of subfunction 2 of main function 100) now supports adding diffuse functions and generating input file of sTD-DFT task.
• .vti file (ParaView VTK Image Data) containing scalar data now can be loaded to provide grid data. This makes Multiwfn able to deal with the magnetically induced ring current data calculated by GIMIC 2.0 code.
• .mol2 file now can be used as input file for EEM charge calculation.
• After using option 6/7/16/17 of sum-over-states module of Multiwfn (subfunction 8 of main function 200), variation of all components of beta/gamma with respect to number of considered states / external frequency will be exported to a text file with _comp suffix in current folder.
• Subfunction 22 of main function 100 now is also able to detect pi-like delocalized orbitals for a not exactly planar system, see updated Section 3.100.22 for detail.
• Multiwfn now is able to directly load .gbw file of ORCA program, the user should set "orca_2mklpath" in settings.ini to actual path of the orca_2mkl executable file in ORCA folder.
• A new option "8 Export all surface vertices and surface extrema as vtx.pqr and extrema.pqr" is added to post-process menu of quantitative molecular surface analysis module. In the exported .pqr files, value of mapped function is recorded as the third last column in high precision and a.u.
• [2019-Aug-8] GROMACS .gro format now can be used as input file to provide atomic information
• [2019-Aug-24] The RDGmap.gnu in "examples" folder has been replaced with examples\scripts\RDGscatter.gnu. As described in the updated Section 3.23.1, before plotting sign(λ2)ρ colored RDG scatter map, the output.txt file is no longer needed to be manually processed.
• [2019-Aug-30] In the function "Obtain NICSZZ value for non-planar or tilted system", the plane can be defined via fitting a given set of atoms (in old version you can only use three atoms to define the plane)
• [2019-Sep-2] When input file contains connectivity information, such as .mol2 and .cml, the bonding in GUI will not be automatically determined but displayed according to known connectivity.
• [2019-Sep-11] In main function 0, if an orbital has been selected, then the file name of saved picture will be the corresponding orbital index.
• [2019-Sep-13] Electron excitation analysis modules (e.g. hole-electron analysis) now supports output file of excited state optimization task of Gaussian and ORCA as input file.
• [2019-Sep-14] In the menu of plotting color-filled map, shaded relief map and colored matrix, now one can change color transition method via option "Set color transition", namely the default rainbow transition (Purple-Green-Red) is no longer the only choice. An illustration is given in Section 4.4.1.2 of the manual. At the meantime, the "inowhiteblack" parameter in settings.ini is removed, because the same effect can be equivalently realized by choosing other color transition method instead of the default one.
• [2019-Sep-19] "iprintLMOorder" parameter is added to settings.ini, if it is set to 1, then after completing the generation of LMOs, composition of LMOs will be printed in the order of atoms and atom pairs instead of in order of LMO indices.
• [2019-Sep-21] Output file of NBO7 now could be used for AdNDP, NAOMO, etc. analyses (Earlier versions only support NBO 3,5,6).
• [2019-Sep-22] In the post-process menu of quantitative molecular surface analysis module, a new option 18 is added, by which you can remove unwanted surface extrema by inputting their indices. Another new option is 19, you can use it to merge some surface extrema, the average coordinate of selected extrema will be employed as the new position.
• [2019-Sep-22] In the population analysis module, if fragment has been defined by option -1, then after population analysis or atomic charge evaluation, not only fragment charge will be given, but also fragment population will be shown.
• [2019-Sep-24] In the post-process menu of hole-electron analysis, an option -1 is added, if its status is manually switch to "Yes", then the outputted cube files (e.g. hole.cub) will have index of currently loaded excited state as suffix.
• [2019-Sep-28] "Toggle showing hydrogens" and "Set atom highlighting" options are added to "Other settings" menu of GUI of main function 0.
• [2019-Oct-12] "isoRGB_same" and "isoRGB_oppo" parameters are added into settings.ini, they are used to set default red, green and blue components of isosurface with same sign and oposite sign as current isovalue, respectively.
• [2019-Oct-19] Customized charge constraint and equivalent constraint now also take effect for the first stage of the standard two-stage RESP fitting procedure. This improvement make RESP charge fitting more flexible.
• [2019-Oct-22] A new parameter "iMCBOtype" is added to settings.ini. If it is set to 1, then the calculated multi-center bond order will correspond to the average between positive and reversed input order of atom indices. If it is set to 2, then all possible permutations of atom indices will be taken into account in the multi-center bond order calculation. See Section 3.11.2 for detail.
• [2019-Oct-29] The function "Decompose Wiberg bond order in NAO basis as atomic orbital pair contributions" introduced in Section 3.11.8 has supported open-shell wavefunction.
• [2019-Oct-30] When outputting calculated Hirshfeld/ADCH/Becke/VDD/CM5 charges, normalized charges are also printed to eliminate the marginal error due to unavoidable inaccuracy of numerical integration
• [2019-Nov-16] The orbital composition analysis function based on natural atomic orbitals (NAOs) now also prints contribution from NAO shells.
• [2019-Nov-21] The sum-over-states module (subfunction 8 of main function 200) now has a new option 19, which is used for scanning w1 and w2 of beta(-(w1+w2);w1,w2), the resulting file can be used to plot "beta vs. w1,w2" relief map to identify possible non-linear optical effects. See Section 4.200.8.1.
• [2019-Dec-2] In the Hirshfeld surface analysis, the area of contact surface between specific atoms in the central molecule and specific atoms in the peripheral molecules can be outputted. See updated Section 4.12.6 of Multiwfn manual for example.
• [2019-Dec-4] The bond orders calculated by Multiwfn now can be easily labelled on molecular structure map by using Multiwfn in combination with GaussView. See updated Section 4.9.1 of manual on how to realize this.
• [2019-Dec-23] A new option "Select fragment" is added to "Tools" submenu of the menu bar of main function 0. After selecting it and input an atom index, the whole fragment where the atom attributes to will be highlighted, and the indices of all atoms in the fragment will be returned. This is useful when you perform analysis based on fragment.
• [2019-Dec-24] The function of generating PSI4 input file (see subfunction 2 of main function 100) now can very easily generate input file of SAPT task. See http://sobereva.com/526 for introduction.
• [2019-Dec-10] The functions for generating input file of PSI4 and MOPAC programs (corresponding options in subfunction 2 in main function 100) have been largely extended
• [2019-Jan-19] Option 9 is added to DOS plotting module, it can be used to show orbital degeneracy in terms of height of discrete lines. See updated examples in Section 4.10.
• [2019-Jan-23] DOS plotting module (main function 10) now support saving current status (plotting settings, fragment definition and orbital information) to a file and loading status from a file, so that you can quickly recover previously saved status. See end of Section 4.10.5 for example.
• [2019-Jan-23] Spectrum plotting module (main function 11) now support saving current plotting settings to a file and loading plotting settings from a file. See updated Section 4.11.3 for example.
• [2019-Jan-24] In MK and CHELPG calculation module, the unit of the coordinate in the file for providing additional fitting centers has been changed to Angstrom (the old version is Bohr)
• [2019-Jan-28 & 2020-Apr-10] "iloadGaugeom" is added to settings.ini. When Gaussian output file is used as input file, if it is set to 1 and 2, then Multiwfn will load final geometry (input orientation and standard orientation, respectively) from this file to obtain atom coordinate information.
• [2019-Jan-30] Spectrum plotting module (main function 11) has supported plotting UV-Vis and ECD spectra for EOM-CCSD task of Gaussian.
• [2020-Feb-8] .dx format has been supported as input file, it is a volumetric data format that can be exported by e.g. Volmap plugin of VMD program.
• [2020-Feb-11] A new option "6 Output orbital overlap matrix in atoms to AOM.txt in current folder" now is available in basin analysis module when electron density is selected as the function for partitioning the basins.
• [2020-Feb-13] .mwfn file is supported as input file and can be exported by some functions (e.g. subfunction 2 of main function 100). This is a new and much better format than others (e.g. wfn/fch/molden) for exchanging wavefunction information. See Section 2.5 of manual for detail. The paper specifically introducing the .mwfn format has been published: ChemRxiv (2020) DOI: 10.26434/chemrxiv.11872524.v1
• [2020-Feb-14] In main function 0, now one can select "Tools" - "Write settings to GUIsettings.ini" to save current visualization state to GUIsettings.ini. In the future, one can use "Tools" - "Load settings from GUIsettings.ini" to retrieve previous visualization state. See Section 3.2 of manual for detail.
• [2020-Feb-21] After generating AIM basins via main function 17, if option 4 is selected, not only localization index and delocalization index matrix will be outputted based on basin indices (like earlier version), but also they will be outputted based on atomic indices.
• [2020-Feb-21] In the output of Mulliken, SCPA, Stout-Politzer and NAO orbital composition analysis, contribution of various angular moment of shells are directly printed.
• [2020-Mar-1] B-N and B-C parameters have been added to HOMA calculation module. B-N parameter has been added to Bird calculation module
• [2020-Mar-20] In the function of exporting orbital wavefunctions (subfunction 3 of main function 200), now one can use such as "h" to choose HOMO, "h-3" to choose HOMO-3, "l+2" to choose "LUMO+2". This improvement makes exporting cube file for frontier orbitals easier.
• [2020-Mar-24] A new option "20 Set number of decimal places for axes" is added to post-process menu of DOS plotting module (main function 10).
• [2020-Apr-18] A new algorithm is employed for calculating atom pair delta-g index in the IGM analysis module. The cost is much lower than before, and at the same time the numerical accuracy is evidently improved.
• [2020-Apr-22] Color of critical points in plane map now can be set by "CP_RGB_2D" parameter in settings.ini.
• [2020-Apr-23] Topology analysis function now can be applied for any real space function that supported by Multiwfn.
• [2020-Apr-23] Option 1 in topology analysis module has been extended. Now a batch of starting points can be directly loaded from a .txt/.pdb/.pqr file, therefore this module now is able to be used to refine the positions of the attractors crudely located by basin analysis module based on evenly distributed grids. See Section 4.2.7 of Multiwfn for example.
• [2020-Apr-23] Option -4 of basin analysis module is extended, now it can also export located attractors as .pqr file and .txt file, in which the function value at the attractors are recorded.
• [2020-Apr-23&29] Option -3 has been added to post-processing menu of main function 4, in this option there are many suboptions used to adjust plotting settings. Option -4 is also added, it is used to save (load) all plotting settings to (from) an external file (.txt).
• [2020-May-9] All electron excitation analyses related to configurational coefficients, such as hole-electron analysis, now support sTDA or sTDDFT task of ORCA. See updated Section 3.21.A of manual for detail. Due to this improvement and extremely fast speed of sTDA/sTDDFT method, electron excitation analyses are feasible for systems consisting of even more than 500 atoms.
• [2020-May-21] Option 3 has been added to orbital localization analysis module (main function 19). This option can localize specific subset of molecular orbitals, making orbital localization more flexible.
• [2020-May-30] In old versions, topology paths do not exactly reach the final critical point. In the new version, the finally nearly reached critical point is regarded as the final point of the path, and thus the reported length of topology paths becomes more reasonable.
• [2020-Jun-2] Calculation of Hirshfeld-I charge becomes significantly easier!!! In the new version, "atmrad" folder is provided in the "examples" directory in Multiwfn binary package, it contains atomic radial densities for all elements in the periodic table (except for lanthanides and actinides) at all possible charged states. If this folder is copied to current folder, then the step of calculating atomic .wfn files will be directly skipped during Hirshfeld-I calculation. See Section 3.9.13 of manual for details and Section 4.7.4 for example.
• [2020-Jun-6] The molden file generated by ORCA and Dalton containing h angular moment now has been perfectly supported.
• [2020-Jun-6] Default extension distance of ICSS analysis has been changed from 6 Bohr to 12 Bohr, which is more reasonable for this kind of analysis.
• [2020-Jun-7] In the RESP charge calculation module, maximum number of RESP iterations and charge convergence threshold now can be set by option 4 in this module.
• [2020-Jun-27] Subfunction 7 of main function 6 now is able to export electric quadrupole and octopole integral matrix between basis functions.
• [2020-Jun-27] In subfunction 21 of main function 100, now one can input "dist" command and then input atom indices for two fragments, then minimum and maximum distances between the fragments, as well as distances between their geometry centers or between their mass centers, will be outputted.
• [2020-Jul-5] In the sum-over-states (SOS) calculation module (subfunction 8 of main function 200), user now can specify incident lights in negative frequencies to compute e.g. beta(-(w1-w2);w1,-w2).
• [2020-Jul-11] Speed of calculating electrostatic potential (ESP) has been significantly improved!!! (faster than old version by more than 20 times) This new code of efficiently evaluating ESP was kindly provided by Jun Zhang and then adapted by Tian Lu.
• [2020-Jul-21] Time spent in loading large .fch/.molden file is notably reduced.
• [2020-Jul-24] When plotting spectra for multiple systems in main function 11, it is no longer need to place the system with maximal number of transitions as the first term in the multiple.txt.
• [2020-Aug-13] The option 1 in conceptual density functional theory analysis module (subfunction 16 of mainfunction 100) now is able to generate ORCA input files for producing N.wfn, N+1.wfn and N-1.wfn. User should select option -2 to switch the program to ORCA before selecting option 1.
• [2020-Aug-14] -nt and -uf arguments now can be added to command line of running Multiwfn to specify number of threads and index of user-defined function, respectively. -set can be used to specify position of settings.ini file. For example, Multiwfn phenol.wfn -nt 12 -set /sob/settings.ini. -silent argument can request Multiwfn run in silent mode. See Section 2.2 for more information.

IMPROVEMENTS ON MANUAL
• [2019-Aug-8] Section 4.18.9 is added to the manual to illustrate how to transform transition density to natural orbitals and export them as .molden and .wfx files.
• [2019-Aug-24] The way of plotting sign(λ2)ρ colored IGM scatter map has been described at the end of Section 4.20.10.1.
• [2019-Sep-14] A new Section 4.4.1.2 is added to the manual to further illustrate skills of plotting plane map.
• [2019-Sep-17] Average local ionization energy (ALIE) colored molecular surface map now can be very easily drawn based on VMD script, see updated Section 4.12 of manual on how to realize this. This kind of map is quite useful for studying possible sites of electrophilic attack.
• [2019-Sep-28] Section 4.200.6.2 is added to the manual to show how to evaluate contribution of lone pair of an atom to various MOs by means of orbital localization analysis and orbital correspondence analysis.
• [2020-Feb-21] Section 4.12.13 is added to the manual to illustrate how to analyze local electron affinity.
• [2020-Mar-1] A document "Calculating information-theoretic quantities and some relevant quantities by Multiwfn" is added to "Resources" page of Multiwfn website. This document briefly illustrates how to use Multiwfn to calculate the very valuable information-theoretic quantities proposed by Prof. Shubin Liu in recent years.
• [2020-Mar-1] "Trick: Perform ESP analysis on molecular surface solely based on cube files" is added to end of Section 4.12.1.
• [2020-Apr-22] A document "How to cite Multiwfn.pdf" is provided in Multiwfn binary package since this version.
• [2020-Apr-23] Section 4.2.7 is added to the manual. This section illustrates how to use attractors determined by basin analysis module as initial guessing points for searching critical points by topology analysis module. This skill guarantees that all maxima of positive part and minima of negative part of a function with complicated distribution can be exactly located.

BUG FIXED
• Fixed: For a molecule of very long chain, the main function 0 is unable to plot the system.
• Fixed: When plotting DOS for beta spin, the vertical dash line does not correspond to beta-HOMO.
• [2019-Aug-28] Fixed: Some functions are incompatible with output file of ORCA 4.2
• [2019-Sep-11] Fixed: For some large systems, the Hirshfeld-I charge is completely wrong or the calculation will crash.
• [2019-Sep-12] Fixed: Multiwfn crash during Hirshfeld surface analysis if atomic densities are evaluated based on atomic .wfn files.
• [2019-Sep-24] Fixed: The outputted new.gjf by simple energy decomposition analysis function (subfunction 5 main function 21) does not work for Linux version of Gaussian16
• [2019-Oct-24] Fixed: Output file of anharmonic analysis of Gaussian program for linear molecule cannot be loaded to plot vibrational spectrum by main function 11
• [2019-Nov-4] Fixed: Cannot normally invoke cubegen to plot electrostatic potential by main function 3.
• [2019-Nov-20] Fixed: The excited state dipole moments outputted by option 4 of subfunction 5 of main function 18 are wrong if the origin of the system is not placed at nuclear charge center.
• [2020-Feb-20] Fixed: Molden file containing certain kinds of transition metals generated by Grimme's xtb code cannot be properly loaded.
• [2020-May-28] Fixed: Unit conversion factor between eV and nm is marginally inaccurate.
• [2020-Jun-28] Fixed: The unsymmetrized transition density matrix (TDM) between two excited states generated by subfunction 9 of main function 18 is incorrect. This bug does not affect symmetrized TDM.

Multiwfn Version 3.6 (Release date: 2019-May-21)

NEW FUNCTIONS
• A very powerful and easy-to-use RESP module is added into main function 7 (Population analysis). It can calculate the well-known ElectroStatic Potential (RESP) charge proposed in J. Phys. Chem., 97, 10269 (1993), and can also calculate ESP fitting charges under various customized conditions such as atomic equivalence constraint and fragment charge constraint. Multiple conformation is fully supported. See Section 3.9.16 for detailed introduction and Section 4.7.7 for examples. This module should be able to bring a revolution in the field of RESP charge derivation.
• Energy decomposition analysis based on UFF/AMBER/GAFF molecular forcefield is supported as subfunction 1 of main function 21. See corresponding introduction in Section 3.24.1 and examples in Section 4.21.1 of the manual.
• A new parameter "cubegenpath" is introduced into settings.ini file. If the parameter is set to actual path of cubegen utility of Gaussian package and the input file is .fch/fchk type, for most analyses of electrostatic potential (ESP), such as plotting plane map of ESP, molecular surface analysis of ESP, the ESP data will be calculated using cubegen instead of internal code of Multiwfn, the overall computational time will be significantly reduced, especially for large systems (since speed of calculating ESP by cubegen is evidently faster than current version of Multiwfn). See Section 5.7 of manual for detail.
• If .chg file is used as input file, now it can be converted to .pqr file using subfunction 2 of main function 100. The .pqr file can be directly loaded into VMD. This feature is very useful if you want to vividly exhibit atomic properties (e.g. atomic charges, atomic spin populations, condensed Fukui function) calculated by Multiwfn by means of coloring atoms. See Section 4.A.10 of the manual for illustration.
• Subfunction 21 of main function 100 is extended, now it can easily calculate molecular length/width/height and diameter. See Section 4.200.21 of the manual for example.
• Raman optical activity (ROA) spectrum now can be plotted via main function 11 based on Gaussian output file, see Section 3.13 for detail and Section 4.11.7 for example.
• Almost all kinds of kinetic energy density (more than twenty) have been supported by Multiwfn as user-defined function 1200. See corresponding part of Section 2.7 of the manual for detail.
• Option -3 is added to MK and CHELPG charges calculation module, by using it, it is able to examine electrostatic potential reproducibility of given atomic charges around the whole system or around specific region, see Section 4.7.8 for example.
• Biorthogonalization between alpha and beta orbitals is supported as subfunction 12 of main function 100. For UHF or UKS wavefunction, after applying this transformation, alpha orbitals will be almost perfectly paired with beta orbitals, so that you no longer need to separately discuss two set of spin orbitals, this makes analysis of orbitals much easier. See Section 3.100.12 for introduction and 4.100.12 of example.
• The aromaticity index defined based on information-theoretic quantities in ACS Omega, 3, 18370 (2018) has been supported as subfunction 12 of main function 15. See Section 3.18.11 for detail.
• The core-valence bifurcation (CVB) index, which is a useful quantity of distinguishing strength and classifying H-bonds, now is supported as subfunction 1 of main function 200, see Section 3.200.1 for introduction and example.
• In main function 19, center position of localized molecular orbitals (LMOs) can be given and directly visualized, see updated Section 4.19.1 for example. In addition, dipole moment of LMOs and bond polarity now can be studied, see Section 4.19.4 for example. Introduction of related theories have been added to Section 3.22.
• The spherically symmetric average ELF and LOL now can be calculated by subfunction 4 of main function 100, see Section 3.100.4 for detail. These quantites are key ingredient of the ELF-tuning and LOL-tuning, which were proposed in J. Comput. Chem., 38, 2258 (2017) and J. Phys. Chem. C, 123, 4407 (2019), respectively.
• A "quick start" document has been added into binary package, it should be particularly useful for new Multiwfn users, since via this they can quickly find needed information for performing common analyses.
• The energy decomposition method proposed by Shubin Liu in J. Chem. Phys., 126, 244103 (2007) has been supported as subfunction 2 of main function 21. Please check Section 3.24.2 for introduction and Section 4.21.2 for example.
• The density-of-states (DOS) plotting module now has a special interface aiming for easily plotting photoelectron spectrum (PES) based on (generalized) koopmans theorem, see Section 3.12.4 for introduction and Section 4.10.4 for example.
• Subfunction 22 of main function 100 has been significantly extended, now it can automatically detect pi orbitals based on localized molecular orbitals for both planar and non-planar systems; moreover, pi composition of any kind of orbitals can be evaluated. This feature makes separate study of sigma and pi electrons extremely easy for any system. See Section 3.100.22 of the manual for detail and Section 4.100.22 for illustrative application.
• Subfunction 16 has been added to main function 100, it can automatically calculate all important quantities defined in the framework of conceptual density functional theory via minimal steps (including Fukui function and dual descriptor as well as their condensed form, Mulliken electronegativity, hardness, electrophilicity and nucleophilicity index, softness, local softness, relative electrophilicity and nucleophilicity, etc.)

UPDATES ABOUT ELECTRON EXCITATION ANALYSIS MODULE

Numerous improvements and changes have been made for main function 18, they are summarized as follows. At the meantime, the corresponding sections of the manual have been significantly rewritten.

• Hole-electron analysis module has been significantly rewritten. Definition of some indices have been changed and the result will be different to older version. This module now supports a new definition for measuring overlap between hole and electron, it is named as Sr, while the old one is named as Sm. Basis function, atom and fragment contribution to hole and electron distribution now can be directly printed. In addition, atom and fragment contribution can be vividly plotted as heat map. See Section 3.21.1 for introduction and Section 4.18.1 for example.
• The Λ (Lambda) index proposed in J. Chem. Phys., 128, 044118 (2008) has been supported as subfunction 14 of main function 18, it has been prevalently employed in literatures to determine type of electron excitations. See Section 3.21.14 for introduction.
• By newly added subfunction 13 of main function 18, natural orbitals for a batch of selected excited states can be generated and exported to .molden file. See Section 3.21.13 for detail and Section 4.18.13 for example.
• The transition density matrix plotting function (subfunction 2 of main function 18) now can plot fragment based TDM map. In addition, this function now can automatically generate TDM between ground state and selected excited state and thus becomes much easier to use. See Section 3.21.2 for introduction and Section 4.18.2 for example.
• The function of generating transition density matrix (TDM) has been moved to subfunction 9 of main function 18. At the meantime, this function now supports generating TDM between two selected excited states.
• Definition of some quantites outputted by subfunction 3 of main function 18 (Analyze charge-transfer based on density difference grid data) has been modified to make the result more meaningful, see Section 3.21.3 for detail.
• Delta_r index now can be calculated for a batch of excited states at one time (subfunction 4 of main function 18).
• Speed of calculating transition electric dipole moment between excited states (subfunction 5 of main function 18) has been remarkably improved.
• In the function "Calculate interfragment charge transfer in electron excitation via IFCT method" (subfunction 8 of main function 18), a batch of fragments now can be simultaneously defined and the result between all fragments are outputted together. Notice that the equation used in this function in older version is incorrect, this problem has been fixed. See Section 3.21.8 for introduction of this method and Section 4.18.8 for example.
• The function "Generate transition density matrix" has been moved to subfunction 9 of main function 18 from hole-electron analysis module. At the meantime, speed of this function was significantly improved.
• The function "Decompose transition electric dipole moment as molecular orbital pairs contribution" has been moved to subfunction 10 of main function 18 from hole-electron analysis module. At the meantime, speed of this function was significantly improved, and the terms can be sorted and outputted according to contribution to transition dipole moment.
• The function "Decompose transition dipole moment as basis function and atom contributions" has been moved to subfunction 11 of main function 18 from hole-electron analysis module.
• The function "Check, modify and export configuration coefficients of an excitation" has been moved to subfunction -1 of main function 18 from hole-electron analysis module. In addition, this function now can export user-modified configuration coefficients to an external file, which can then be directly used as input file for all subfunctions in main function 18.
• Output files of TDDFT task of Firefly and GAMESS-US programs are fully supported as input file for all kinds of electron excitation analyses, see beginning of Section 3.21.
• Option 4 is added to subfunction 5 of main function 18. This option is able to calculate dipole moment for all excited state at once.
• Generating transition density and transition dipole moment density between two excited states is available now, see Section 4.18.2.3 for example.

IMPROVEMENTS AND CHANGES
• Calculation speed of charge decomposition analysis for large systems has been significantly improved.
• Section 4.A.13 has been added to manual, it describes how to very easily plot pretty ESP colored molecular vdW surface map as well as penetration map of monomer vdW surface in VMD program based on output file of Multiwfn.
• Section 4.2.5 has been added to the manual, it describes how to very easily plot pretty AIM critical points and topology paths in VMD program based on output file of Multiwfn.
• In the MK and CHELPG module, if option 6 as been chosen once, then after calculation, fitting points with exact ESP value or absolute difference between the exact ESP and the ESP evaluated by atomic charges can be exported to .pqr file, which can be directly render in VMD. The example in Section 4.7.8 utilized this feature.
• Algorithm detail of ADCH atomic charge has been changed, see Section 3.9.9 of the manual for detail. If the system has local planar (or almost planar) regions, the ADCH charges in these regions obtained via the new version may be different to those obtained via older versions. The result produced by the new version should be more reasonable. Similarly, the result of atomic dipole moment corrected Becke charges is also different to the older versions.
• .pqr file is supported as input file. For Multiwfn, the information provided by .pqr and .chg is the same, namely atom information as well as atomic charges, see Section 2.5 of the manual.
• Output file of Firefly has been experimentally supported. After changing the suffix of output file of Firefly to .gms, the file can be directly loaded into Multiwfn to provide wavefunction information.
• Molden input file produced by NWChem has been formally supported. See beginning of Chapter 4 of the manual on how to properly generated it.
• Option 8 is added to post-process menu of main function 4 for most kinds of plane maps. Using this option, chemical bonds can be drawn on the graph as straight lines.
• When using Independent Gradient Model (IGM) anaylsis, if your input file contains wavefunction information, the program will let you choose the kind of the sign(lambda2)rho to be used, the first one is that based on actual electron density, the second one is that based on promolecular density.
• Section 4.7.6 is added to the manual, in which I discussed how to easily determine correspondence between basis functions and atomic orbitals via Mulliken population analysis.
• Section 4.4.9 is added to the manual to illustrate how to plot LOL-pi map for porphyrin to reveal favorable electron delocalization path.
• Section 4.2.4 is added to the manual to illustrate how to decompose properties at a critical point or given point as orbital contributions.
• Interface of Mulliken population analysis (MPA) is improved, meantime Section 4.7.0 is added to the manual to illustrate the use of MPA.
• When outputting vtx.pdb in post-process menu of quantitative molecular surface analysis, for electrostatic potential analysis, if value at any surface vertex exceeded recording limit of B-factor field of .pdb file, eV will be used instead of kcal/mol.
• Content of Section 4.12.7 of the manual has been replaced, now it corresponds to a newly added example, namely illustrating how to predict density of molecular crystal based on result of quantitative molecular surface analysis
• Section 4.17.1 of the manual is extended to illustrate how to carry out AIM basin analysis for the systems containing pseudoatoms (non-nuclear attractors of electron density)
• After integrating specific domain in domain analysis module (subfunction 14 of main function 200), minimum and maximum X/Y/Z of points belonging to the domain, as well as span distance in X/Y/Z will be outputted. In addition, option 11 is added to post-process menu, which is used to export boundary grids of specific domain to a .pdb file, so that you can easily use such as VMD program to measure size of the domain. These updates are quite useful for characterizing molecular cavity (see Section 4.200.14.2 of the manual)
• In the interface of defining fragments for plotting PDOS and OPDOS, the fragments now can be directly defined according to angular moment of atomic orbital. Meantime, the DOS plotting example in Section 4.10 has been extended to reflect this improvement
• Subfunction 28 is added to wavefunction modification module (main function 6), it is used to modify orbital energies. This function is useful when you want to rectify the orbital energies using a given relationship (e.g. J. Am. Chem. Soc., 121, 3414 (1999)) before plotting density-of-states (DOS) map.
• Section 4.A.7 has been added to the manual to show how to study polarizability and hyperpolarizability densities by Multiwfn. This method is important for studying local contribution to (hyper)polarizability.
• Section 4.9.5 has been added to the manual to illustrate the usefulness of decomposition analysis of Mulliken bond order.
• The atomic radii used in MK and CHELPG charge fitting now can be set via option 10 in corresponding interface. The default radii of Na, Mg, Al, Si used in MK fitting have been modified (the older ones are not quite reasonable).
• Options 7 and 8 are added to post-process menu of IGM module. They are used to set delta_g and delta_g_inter where sign(lambda2)rho is out of specific range. Obviously, by these options you can screen unwanted regions from isosurface map of delta_g and delta_g_inter map.
• "imodlayout" in settings.ini now can be set to 2, the layout of all GUI will be very suitable for 1024*768 resolution.
• The option "2 Delete some CPs" in subfunction -4 of topology analysis module has been significantly extended, now it can also delete CPs according to type and distance to a given molecular fragment.
• Using the newly added option "10 Set the atoms to be considered in searching modes 2, 3, 4, 5" in subfunction -1 of topology analysis module, one can only search CPs in a given molecular region.
• Subfunction 9 of main function 100 now can evaluate and print index for measuring interatomic connectivity.
• When calculating AdNDP and LMO orbital energies, Fock matrix now can be directly loaded from $FOCK field of NBO .47 file.
• Generation of path in topology analysis module has been parallelized, the speed is improved significantly!
• New parameter "plotwinsize3D" has been added to settings.ini, it controls the size of the plotting region for 3D objects in GUI
• The .fchk files generated by PSI4 since 1.2 have been formally supported, and the way of analyzing CCSD(T) wavefunction generated by PSI4 has been changed, see Section 4.A.8 for detail.
• When showing orbital list in console window via "Orbital info." option of main function 0, for beta orbitals, now the index counted from the first beta orbital is also shown.
• Main function 11 now is able to plot spin-orbit coupling corrected (SOC) UV-Vis and ECD spectra based on SOC-TDDFT calculation of ORCA 4.1. See Section 3.13.2 of detail and Section 4.11.6 for example.
• In main function 1, when you request Multiwfn to print properties at nuclear position of an atom, the electrostatic potential without contribution of nuclear charge of this atom now is simultaneously printed (this quantity at hydrogen site is useful in pKa studies, because it measures binding strength between this proton and rest of the system). Due to this update, the procedure of the example in Section 4.1.2, which introduces how to predict intermolecular interaction energy based on ESP at nuclear position, has been significantly simplified.
• Thickness of lines/curves/axes/texts in spectrum plotting module (main function 11) now can be set by the newly added option 22.
• The molden input file generated by Grimme's xtb code has been supported.
• In the GUI windows showing 3D objects, now one can zoom in and zoom out the perspective by rotating mouse wheel on the drawing region.
• In the GUI of showing structure and orbitals (main function 0), the "Other settings" in the menu bar has been extended significantly. Its options now is able to choose atomic label type, atomic label color, set lighting and select predefined drawing style (CPK, vdW, line)
• In the GUI of topology analysis, label color of critical points and atoms now can be set via "Set label color" in the menu bar.
• Section 4.A.11 is added to the manual, this section presents an overview of all methods supported by Multiwfn that can be used to discuss chemical bonds.
• .gjf is now supported as input file, it can provide atomic coordinate information to Multiwfn.
• Magnitude of electric field is added as the 103th user-defined function.
• .mol2 is supported as input file.
• .chk file can be directly loaded as long as you have set "formchkpath" in settings.ini to actual path of formchk executable file in Gaussian package.
• Section 4.11.8 is added to the manual, it describes how to extremely easily plot spectrum for a batch of files via shell script
• For unrestricted wavefunction, now one can plot various kinds of DOS maps for alpha and beta spin simultaneously. The spin can be chosen via option 6 in DOS plotting interface.
• cube file with non-rectangle grid now can be loaded, however, in this case only the grid data calculation function in main function 13 could be normally used.
• In the AdNDP module, the option used to export cube files has been improved.
• The rarely used subfunction 7 of main function 100 is removed. Instead, when user export Gaussian .gjf using the subfunction 2 of main function 100 and meantime wavefunction is presented, the wavefunction can be written into the .gjf as initial guess.
• The interface of outputting ORCA input file (option 12 of subfunction 2 of main function 100) now is able to specify commonly used level and type of task.
• The function for calculating intermolecular orbital overlap integral is no longer limited for Gaussian users, see updated Section 3.100.15 of manual for detail.
• The default integration grid for computing orbital composition via Hirshfeld/Hirshfeld-I/Becke has been slightly changed to make result evidently more accurate for orbitals showing Rydberg character
• In the orbital localization module (main function 19), now Hirshfeld is employed as the default method to automatically compute composition of the resulting LMOs, it is more robust than the Mulliken+SCPA method used in earlier verison and compatible with diffuse functions.
• The method of calculating orbital composition for LOBA analysis has been changed to Hirshfeld, which is more robust than the SCPA method used in earlier version.
• In the DOS plotting module (main function 10), Hirshfeld and Becke methods have been supported for calculating orbital compositions, which are more robust than the Mulliken/SCPA method used in earlier version and compatible with diffuse functions. See Part 6 of Section 4.10.1 for example.
• More options have been added to the post-process menu of DOS plotting module to make it more flexible, and many improvements have been made to make graphical effect better.
• A section 4.A.14 has been added to manual, it introduces a way of very easily rendering cube files produced by Multiwfn as state-of-the-art isosurface map via VMD script.
• Option 13 has been added to post-process menu of quantitative molecular surface analysis module. Via this new option one can easily plot pretty color-mapped Hirshfeld/Becke surface isosurface via VMD program to illustrate intermolecular interactions, see updated Section 4.12.6 for example.
• Overband and combination band of IR, VCD and Raman spectra now can be plotted by main function 11 based on output file of corresponding Gaussian anharmonic tasks.
• Option -1 has been added to the plotting plane definition interface of main function 4. By this option you can set translation and rotation of the plotting plane. This point has been mentioned in Section 3.5.2 of the manual, a practical instance of using this option was posted on http://bbs.keinsci.com/thread-11037-1-1.html.
• Subfunction 8 is added to option -5 of topology analysis module, it is used to only retain bond paths (and corresponding BCPs) connecting two fragments but remove all other bond paths, so that one can more easily study interfragment interactions via AIM method. See Section 4.2.6 for illustration this option.

BUG FIXED
• Fixed a fatal bug in the calculation of beta, gamma and delta via sum-over-states (SOS) method. This bug was introduced since version 3.5.
• Due to some bugs in EDFlib library, (3,+3) rather than (3,-3) type of AIM critical points are located at nuclear position for some elements when pseudopotential is employed. This problem has been fixed via updating EDFlib.
• When drawing spectra for multiple systems based on .dat file outputted by Grimme's sTDA program, Multiwfn crashes. This problem has been fixed.
• When custom operation involves "+" operator, the program doesn't work. This problem has been fixed, thanks jimkress for reporting.
• GAMESS-US output file cannot be loaded properly when pseudopotential is used, this problem has been solved, thanks PedroS for reporting.
• The sign of Coulomb attractive energy (exciton binding energy) outputted by hole-electron analysis module has been inverted, now this quantity is always positive to in line with literature convention.
• Local DOS map for beta part of unrestricted wavefunction is incorrect, this problem has been fixed.

Multiwfn Version 3.5 (Release date: 2018-Apr-6)
NEW FUNCTIONS
* A new main function 20 is added, which is a collection of all visual study methods for weak interaction. It can carry out NCI (with/without promolecular approximation), aNCI, DORI, which have already been supported in eariler version, and the newly supported IGM analysis. The corresponding parts of the manual are completely rearranged and largely rewritten.
* The Independent Gradient Model (IGM) analysis method proposed in Phys. Chem. Chem. Phys., 19, 17928 (2017) is fully supported and can be performed via subfunction 10 of main function 20. This method can be used to individually visualize intra-fragment and inter-fragment interactions, the contribution of atomic pairs and atoms can be quantified and vividly rendered with help of VMD. In addition, the delta_g function involved in IGM analysis is added as the 22th real space function, its value at bond critical point in weak interaction region is shown to be closely related to interaction strength. See Section 3.22.5 of manual for introduction of IGM method, analysis examples are given in Section 4.20.10.
* Orbital localization analysis module (subfunction 13 of main function 200 in older version) is greatly improved and extended, now it is appeared as main function 19 since it is frequently used. Foster-Boys localization method and Pipek-Mezey localization with Lowdin population are added. In addition, the speed of Pipek-Mezey localization is signifcantly improved compared to older version, now it can be easily used for localizing occupuied orbitals for a system containing about 200 atoms. Moreoever, major character of resulting LMOs are automatically printed so that the users can quickly find the orbitals they are interested in.
* The total/dynamic/nondynamic electron correlation index proposed in Phys. Chem. Chem. Phys., 18, 24015 (2016) have been implemented as subfunction 15 of main function 200. Details can be found in Section 3.200.15 of the manual. .wfn/.wfx/.molden file carrying natural orbitals could be used as input file.
* CCSD(T) wavefunction generated by PSI4 program and arbitrary order of coupled-cluster and CI wavefunctions (including FCI) generated by Kallay's MRCC program can be analyzed by Multiwfn. See Section 4.A.8 of the manual for detail.
* Section 4.18.5 is added to manual, this section describes how to plot transition dipole moment contributed by molecular fragments as arrows in VMD program based on the data outputted by hole-electron analysis module of Multiwfn.
* In main function 1, if input "d", real space function value at a given point can be decomposed into contribution of various orbitals, see Section 3.3 for details. Property decomposition for critical points is also supported in option 7 of topology analysis module.
* MDL molfile (.mol) is supported as input file.
* Electronegativity Equalization Method (EEM) charge now can be easily calculated via suboption 17 of main function 7, see Section 3.9.15 for introduction and Section 4.7.5 for example. Atomic charges of a system composed of hundreds of atoms can be obtained instantly via this method.
* In main function 18, subfunction 8 is added to calculate amount of interfragment charge transfer between any two fragments during electronic excitation, see Section 3.21.8 for detail and 4.18.6 for example.
* Subfunction 22 of main function 100 is significantly extended, now it enables automatically detecting pi orbitals based on localized molecular orbitals for both planar and non-planar systems. This feature makes separate study of sigma and pi electrons quite easy for all kinds of system. See Section 3.100.22 of the manual for detail and Section 4.100.22 for illustrative application.
* Subfunction 9 is added to main function 9, this function can decompose Wiberg bond order in NAO basis as contributions from NAO orbital pairs and NAO shell pairs, and thus makes interactions between atomic orbitals and atomic shells that play key role of covalent bonding can be clearly revealed. See Section 3.11.8 of the manual for details and Section 4.9.4 for example.
* Main function 11 now can plot IR spectrum by using output file of Grimme's xtb program (https://www.chemie.uni-bonn.de/pctc/mulliken-center/software/xtb/xtb) as input file.
* Subfunction 16 is added to main function 200. This function is used to generate natural orbitals, spin natural orbitals and natural spin orbitals based on the density matrix in .fch/.fchk file. See Section 3.200.16 for details.
* Option 5 of subfunction 1 (hole-electron analysis module) of main function 18 now can output atom-atom contribution matrix of transition electric/magnetic dipole moment, and it can be further plotted as colored matrix map. See corresponding description in Section 3.21.1.3.
* Function -2 is added to main function 7 (population analysis module). Using this function the electrostatic interaction energy between two fragments can be calculated based on atomic charges. .chg file should be used as input file since this file records atomic charge information.
* The Strong Covalent Interaction index (SCI) proposed in J. Phys. Chem. A, 122, 3087 (2018) is added as the 37th user-defined function, see entry 37 of Section 2.7 for introduction, this function is shown to be very useful for identifying very strong covalent bonds.
IMPROVEMENTS AND CHANGES
* Molden input file produced by Dalton is formally supported
* Mode 10 is added to the interface for setting up grid data, this mode allows the box to be defined in a GUI window, the position and size of the box can be visually defined and thus very convenient.
* Section 4.200.14.2 is added to the manual to illustrate how to use domain analysis module to visualize molecular cavity and calculate cavity volume.
* Section 4.19.2 is added to the manual to illustrate how to study variation of localized molecular orbitals (LMO) during chemical reaction. Section 4.19.3 is added to illustrate how to use LMO to analyze Re-Re quadruple bond in [Re2Cl8]2-.
* .molden file generated by ORCA with g angular moment basis functions now can be directly used as input file (without employing Molden2aim).
* "Set perspective" option is added to menu of all GUI windows for showing molecule, via this option one can exactly adjust viewpoint. In addition, in the GUI for showing relief map, text boxes are added to exactly control viewpoint.
* In Section 3.20.1 of Multiwfn manual, the way of plotting color-filled "RDG vs sign(lambda)rho" scatter map for studying weak interaction using NCI method is described.
* The functions 4,5,6 in hole-electron analysis module of Multiwfn is fully parallelized, the time cost is significantly lowered for large system.
* After booting up Multiwfn, if directly pressing ENTER button, a GUI window will be shown used to select input file.
* The built-in EDF library is updated (now it corresponds to molden2aim 4.1.4).
* Section 4.A.9 is added to manual. It describes how to calculate TrEsp (transition charge from electrostatic potential, see J. Phys. Chem. B, 110, 17268), and how to calculate excitonic coupling energy between two molecules based on TrEsp charges.
* Option -5 is added to orbital localization module, it can be used to switch if considering core orbitals during localization of occupied orbitals. If core orbitals are ignored, the cost for medium or large-size system can be significantly reduced.
* When calculating ESP fitting charges (MK, CHELPG...), if radius of some elements are not predefined, now one can directly press ENTER button to use corresponding UFF radius multiplied by 1/1.2, this is often a reasonable choice.
* Speed of calculating transition dipole moment between excited state (subfunction 5 of main function 18) is greatly improved.
BUG FIXED
* For open-shell cases, the multi-center bond orders calculated based on NAO basis are not correct (prefactor is missing), this problem has been fixed.
* The sign of Mulliken transition charge outputted by hole-electron analysis module is not correct in the older versions, it should be multiplied by -1 to meet common convention. This problem has been fixed.

Multiwfn Version 3.4.1 (Release date: 2017-Oct-25)
NEW FUNCTIONS
* The local total/dynamic/nondynamic electron correlation function proposed in J. Chem. Theory Comput., 13, 2705 (2017) now is supported as user-defined function 87,88,89, respectively. These functions are useful for vividly revealing electron correlation in various molecular regions. See corresponding entries in Section 2.7 for detail. Illustrative application is given in part 2 of Section 4.A.6.
* Spectrum of multiple systems now can be easily plotted together, see Section 4.11.6 for example.
* subfunction 2 of main function 100 now can yield basic input file for a batch of known quantum chemistry codes including Gaussian, GAMESS-US, ORCA, MOPAC, Dalton, MRCC, Molpro, NWChem, PSI, CFOUR based on present geometry and charge/multiplicity.
* The CM5 charge proposed by Truhlar et al. in J. Chem. Theory Comput., 8, 527 (2012) has been supported as subfunction 16 of main function 7. See Section 3.9.14 of the manual for detail.
* The ghost-hunter index proposed by Adamo et al. in J. Comput. Chem., 38, 2151 (2017) is supported, it is automatically printed after hole-electron analysis is finished, see Section 3.21.7 of the manual for introduction. This index is useful to judge if an excited state calculated by TDDFT may be regarded as artificial ghost state.
* Gradient norm and Laplacian of electron density are added as user-defined function 79 and 80, respectively. The former is evaluated analytically, while the latter is evaluated semi-analytically.
* Electron delocalization range function EDR(r;d) and orbital overlap distance function D(r) are supported, the code is kindly contributed by Arshad Mehmood. Introduction is given as entry 20,21 of Section 2.6, illustrative examples can be found in Section 4.5.6, 4.5.7 and 4.12.8. Related references: J. Chem. Phys., 141, 144104 (2014); J. Chem. Theory Comput., 12, 3185 (2016); Angew. Chem. Int. Ed., 56, 6878 (2017).
IMPROVEMENTS AND CHANGES
* ORCA output file (CIS or TDA-DFT) has been formally supported for hole-electron analysis module, delta_r calculation module, NTO module and the module used to calculate transition dipole moment between excited states, see Section 3.21.1.2 for detail about the requirement on the input file. (TDDFT/TDHF output file may also be used, however, the result may be unreasonable when de-excitation is significant, see Section 3.21.1.2 for explanation)
* Output file of ORCA sTDA and sTD-DFT calculation now can be used as input file for plotting UV-Vis or ECD Spectrum via main function 11
* Better compatible with G16
* Anharmonic Raman and Anharmonic VCD spectra now can be plotted by main function 11 based on Gaussian output file of freq(raman,anharm) and freq(VCD,anharm) task, respectively (the latter is available only for G16)
* Main function -2 and -3 have been merged into main function 6 as subfunction -2 and -3.
* In subfunction 13 and 14 of main function 13, fragments can be directly defined by inputting atomic indices without preparing atomic list files. This change makes use of these functions more convenient.

Multiwfn Version 3.4 (Release date: 2017-Jun-13)
NEW FUNCTIONS
* Hirshfeld-I (i.e. iterative Hirshfeld) is supported to calculate atomic charges, orbital composition and perform fuzzy space analysis. Please check Section 3.9.13 of the manual for introduction of its theory and implementation. Illustrative examples of using Hirshfeld-I to calculate atomic charges is given in Section 4.7.4
* Single exponential decay detector (SEDD) and density overlap regions indicator (DORI) proposed in J. Chem. Theory Comput., 10, 3745 (2014) are supported as user-defined function 19 and 20, respectively. The advantage of DORI is that it can simultaneously reveal covalent and non-covalent interaction regions, and the pattern is similar to ELF+RDG. An example of using DORI is given at the end of Section 4.100.1.
* On-top pair density is supported as user-defined function 36.
* X, Y, Z component of Hamiltonian kinetic energy density have been added as 81, 82, 83th user-defined function, respectively. The counterpart of Lagrangian kinetic energy density have been supported as 84, 85, 86th user defined function, respectively.
* A new method to define plotting plane is added to main function 4 as mode 7. Via this mode one can directly define a plane parallel to a bond and meantime normal to a plane defined by three atoms. See Section 3.5.2 of the manual for detail.
* Pre-resonance Raman spectrum now can be plotted by option 2 of main function 11. Program will prompt the user to select the interested frequency of incident light.
* Subfunction 11 of main function 100 is greatly extended, now it can calculate both centroid distance and overlap between two orbitals. See Section 3.100.13 of the manual for details.
* By using option 4 and 8 of subfunction 2 of main function 100, .wfx file and NBO .47 file can be exported, respectively, the former is input file of GENNBO program.
* Pipek-Mezey orbital localization is supported as subfunction 13 of main function 200, please check Section 3.200.13 for detail and 4.200.13 for example.
* Energy of AdNDP orbitals now can be printed. Please check Section 3.17 for detail, the AdNDP examples in Section 4.14.1 and 4.14.3 have been correspondingly updated.
* Any real space function now can be integrated within isosurface of a given real space function by subfunction 14 of main function 200. Please check Section 3.200.14 of the manual for detail and Section 4.200.14 for example.
* A powerful EDF library provided by Wenli Zou is built-in. Now by default, if input file contains atoms using pseudopotential basis set, Multiwfn will automatically find proper EDF information for them to provide representation of inner-core density. See Appendix 4 of the manual for detail. (For .wfx file produced by Gaussian, by default Multiwfn still loads EDF field from this file rather than from the built-in EDF library).
* Natural transition orbital (NTO) analysis is supported as subfunction 6 of main function 18, please check Section 3.21.6 for detail and Section 4.18.4 for example.
* Coulomb attractive energy between hole and electron of an electronic excitation now can be calculated at post-process menu of subfunction 1 of main function 18, please check Section 3.21.1 for detail. The example in Section 4.18.1 is correspondingly updated.
* Conformational weighted spectrum and spectrum of multiple conformations now can be very conveniently plotted by main function 11. Please check Section 3.13.4 for detail and Section 4.11.4 for example. In addition, option 4 and 5 of spectrum plotting interface is improved, namely when changing setting of Y-axis at one side, you can choose to proportionally update range of Y-axis at another side so that their zero points are always in the same horizonal line.
IMPROVEMENTS AND CHANGES
* 32bit Windows version of Multiwfn will no longer be released. Since Multiwfn 3.4 only 64bit version will be released.
* The graphical effect of isosurface plotting has been improved, especially for transparent style
* When drawing isosurface with Linux and MacOS version, the requirement of the equal number of grids in X,Y,Z is removed.
* The style of atomic labels in plane map drawn by main function 4 now can be directly set by option 18 in post-process menu
* Two useful ways to check sanity of wavefunction are introduced as Appendix 5 of the manual
* The function of loading NBO plot file becomes more robust.
* .wfn file generated by Windows version of ORCA 4.0 is supported, and that generated by old version of ORCA is no longer supported
* GAMESS-US output file now can be used as input file (not comprehensively tested, currently only single point task at HF/DFT level is formally supported). The suffix of output file should be changed to .gms so that Multiwfn can properly recognize it
* Subfunction 7 of main function 6 now can output various kinds of integral matrix between basis functions, including overlap integrals, electric/magnetic dipole moment integrals, kinetic energy integrals and velocity integrals
* Density matrix in .fch will no longer be tentatively loaded since this version
* Atomic index in .molden file now is interpreted by Multiwfn as nuclear charge. Therefore, when pseudo-potential is used, you can manually change atomic index in the file so that Multiwfn can correctly recognize actual nuclear charge
* Loading speed of .fch and .molden file for large wavefunction is significantly improved
BUG FIXED
* Fixed a bug when loading NBO plot file with mixed spherical and cartesian shells.

Multiwfn Version 3.3.9 (Release date: 2016-Sep-18)
NEW FUNCTIONS
* Region of Slow Electrons (RoSE), which was proposed in Chem. Phys. Lett., 582, 144 (2013), now is supported as the 18th user defined function.
* Subfunction 100 is added to main function 8, this new function implements the LOBA method (Phys. Chem. Chem. Phys., 11, 11297) for evaluating oxidation state based on localized MOs. See Section 3.10.7 of the manual for introduction and Section 4.8.4 for example.
* Subfunction 20 is added to main function 100. This function is used to calculate Hellmann-Feynman force at each nucleus. See Section 3.100.20 of the manual for details.
* Option -1 added to population analysis module for defining fragment. Once the fragment is defined, after the calculation of atomic charges, the fragment charge will be printed together.
IMPROVEMENTS AND CHANGES
* In the output of multi-center bond order calculation, the result in normalized form is printed, this makes multi-center bond order comparable for different ring sizes. In addition, for open-shell cases, the definition of alpha and beta multi-center bond orders changed and became more meaningful by taking a ring-size dependent prefactor into account. see Section 3.11.2 of the manual for details. The definition of multi-center DI is similarly changed, see Section 3.18.10.
* Now it is possible to compile Multiwfn without GUI supported, please check "COMPLIATION METHOD.txt" in source code package. In this case you don't need Dislin and Openmotif graphical library when running and compiling Multiwfn.
* Windows 10 is now formally supported. In Win10, old version of Multiwfn will get stuck for about 1~2 minutes when first time enter GUI.
* Output file of Gaussian excited state optimization task now can be directly used as input file of main function 11 for plotting electronic spectrum.
* After performing quantitative molecular surface analysis, the density estimated according to mass and molecular volume is outputed.
* In option 1 of topology analysis module, user now can input two atomic indices, then corresponding midpoint will be taken as starting point for locating CP. This improvement faciliates locating specific BCP.
* min(A,B) operation is added to option 11 of main function 13, which is useful for evaluating overlap between function of two moieties. Section 4.13.7 is correpondingly added to manual to illustrate using this feature to evaluate electron density overlap region between two methanes.
* When drawing gradient lines map by main function 4, the line width of gradient lines now can be set by option 14 in post-process menu.
* In main function menu, users now can directly use option -11 (a hidden option) to reload a new file.
* In option 1 of subfunction 5 of main function 100, the maximum pairing between Alpha and Beta orbitals of unrestricted wavefunction now can be shown.
* iatmlabtype3D parameter is added to settings.ini, one can choose if atomic labels or indices will be shown in 3D map.
BUG FIXED
* Solved crash problem when performing multi-center bond order analysis based on NBO6 output in case of presence of linear dependency of basis functions.
NOTICE
* Multiwfn now can be installed on OS X EI Capitan, see https://wiki.ch.ic.ac.uk/wiki/index.php?title=Mod:multiwfn, thanks Henry Rzepa for sharing his experiences!

Multiwfn Version 3.3.8 (Release date: 2015-Dec-1)
NEW FUNCTIONS
* Local DOS now can be plotted, see Section 3.12.4 for detail and Section 4.10.2 for example. LDOS can be drawn in terms of DOS curve for a point or color-filled map for a set of points in a given line.
* Option 6 is added to CDA module, by which contribution of each fragment orbital pair to d,b,r terms of CDA can be printed, this greatly faciliates analysis of interaction between fragment orbitals.
* Subfunction 2 of main function 100 now is able to output GAMESS-US input file with/without the SCF initial guess ($VEC) corresponding to present wavefunction. In addition, this function now is able to export .fch file based on present wavefunction, thus Multiwfn could be used as a .molden->.fch converter.
* Option 9 is added to basin analysis module, by this function you can obtain atomic contribution to population number of ELF or other kind of basins, see Section 4.17.7 of the manual for example.
* Energy index (EI) and bond polarity index (BPI) defined in J. Phys. Chem., 94, 5602 (1990) now can be calculated by subfunction 12 of main function 200. See Section 3.200.12 for introduction and 4.200.12 for example. BPI is a useful indicator for bond polarity, and group electronegativity can be evaluated by calculating EI for radical.
IMPROVEMENTS AND CHANGES
* Section 4.A.6 is added to manual, it introduced how to plot odd electron density in Multiwfn.
* When performing topology analysis for electron density in main function 2, the option 0 now clearly show the correspondence between each (3,-3) CP and nucleus.
* Option 19 is added to main function 11, which is used to convert Raman activities to intensities, see Section 3.13.1 for discussion about the difference between activities and intensities.
* Option 20 is added to main function 11, which is used to manually modify strength data. This option is useful if you would like to plot fluorescence spectrum, in this case you need to set oscillator strength of all transitions except for the lowest excitation to zero (Kasha's rule).
* A new suboption (9) is added to option -1 of topology analysis module. By making use of this option, during the critical point (CP) searching, only the CP with value within user-defined range will be reserved, and thus unnecessary CPs could be ignored.
* Subfunction 10 of main function 200 now can be directly used to calculate various kinds of integral for two specific orbitals.
* Subfunction 5 of main function 100 is extended, now the overlap between alpha orbitals and the counterpart beta orbitals are allowed to be directly obtained (i.e. the off-diagonal terms will not be evaluated to significantly reduce cost).
* Option 5 in subfunction 1 of main function 18 now is also able to decompose both transition electric and magnetic dipole moments to basis function and atom contributions.
* In fragment definition interface of DOS plotting and orbital composition analysis modules, when using "cond" method to add wanted basis functions, the P,D,F,G,H shells can be directly selected.
* |V(r)|/G(r) is added as the 35th user defined function. In J. Chem. Phys., 117, 5529 (2002) it was proposed that this quantity at BCP can be used to discriminate interaction types.
BUG FIXED
* The quality of relief map for some real space functions is improved.
* Fixed a small bug in loading .xyz file.
* Fixed a small bug in locating settings.ini file via Multiwfnpath environment variable.
* Expired links containing "hi.baidu.com" in old version of manual have been updated.
* ICSS module (Subfunction 4 of main function 200) now works for G09 D.01. The older version crashes because G09 D.01 changed output format of NMR task.

Multiwfn Version 3.3.7 (Release date: 2015-Mar-22)
NEW FUNCTIONS
* Subfunction 11 is added to main function 200, which is used to calculate center, the first and second moments of a real space function, see Section 3.200.11 of Multiwfn manual for detail.
* The 54th user-defined function is added, see manual.
* If irreducible representation of MOs are properly recorded in .molden file, then in the option 35 of main function 6, one can choose if discarding contribution of some irreducible representations in succeeding analyses. See Section 3.8 of the manual for detail.
IMPROVEMENTS AND CHANGES
* Main function 11 now can plot UV-Vis, IR, Raman and ECD spectra directly based on output file of ORCA program.
* The output file tda.dat of Grimme's sTDA program (http://www.thch.uni-bonn.de/tc/index.php?section=downloads&subsection=sTDA&lang=english) now can be used as input file of main function 11 to plot UV-Vis and ECD spectra. The sTDA method reduces the computational cost of the electronic excitation part of TDDFT calculation by about two or three orders of magnitude.
* In the fragment definition interface of DOS plotting module, the fragment setting now can be import from or export to plain text file.
* The output of function 5 of main function 100 is adjusted and becomes more readable.
* Option -5 is added to fuzzy analysis module, which is used to define the atoms to be integrated (in function 1) and for which the atomic multipole moments will be evaluated (in function 2).
* Function 7 of main function 200 is improved, which is used to parse the (hyper)polarizability output of Gaussian09. Now, when multiple frequencies are specified in frequency-dependent "polar" task, the users can make Multiwfn parse the result at specific frequency. In addition, parsing Beta(-w;w,0) or Beta(-2w;w,w) can be fully controlled by users.
* Molden input file with SP shells is supported.
BUG FIXED
* If pure Gauss functions are involved in open-shell calculation and the corresponding NBO plot file is used as input, the label of orbital type of the orbitals will be slightly incorrect, this bug has been fixed.
* When loading .xyz file the elements with two letters may be erroneously determined, this bug has been fixed.
* Not all legends of defined fragments can be normally shown in PDOS map, this bug has been fixed.
* Sometimes when visualizing isosurface there is an annoying vertical color strip at the boundary of the visible region, this problem has been solved.
* For Mac OSX, the segmentation fault due to stack memory flow when loading large system is solved.

Multiwfn Version 3.3.6 (Release date: 2014-Nov-20)
* The capacity of function 10 in main function 200 has been substantially extended. Now it can output electric/magnetic dipole moment, velocity, kinetic energy and overlap integrals between molecular or other kinds of orbitals. At the same time, the bug of magnetic dipole moment integrals has been fixed.
* Sections 4.A.5 and 4.1.2 are added to the manual, the former summarized the methods for studying weak interactions in Multiwfn, the latter discussed how to make use of ESP at nuclear positions to predict electrostatic dominated weak interaction energies.
* Option -9 is added to post-process menu of main function 4, by which you can plot the graph only for the regions around interesting atoms.
* Bond degree parameter E(r)/rho(r) is added as the 17th user-defined function, see J. Chem. Phys., 117, 5529 (2002) for detail.
* Fixed a crashing problem when visualizing orbitals via main function 0 in Linux environment.
* Parameter "imodlayout" is added to settings.ini. If in Windows environment the orbital list of main function 0 cannot be fully shown, then you can set it to 1 to use alternative layout to solve the problem.

Multiwfn Version 3.3.5 (Release date: 2014-Aug-12)
NEW FUNCTIONS
* The potential acting on one electron in a molecule (PAEM) has been supported as the 33 and 34th user-defined functions, see corresponding part in Section 2.7 of the manual for detail. In addition, the PAEM-MO analysis proposed in JCC, 35, 965(2014) now can be realized in Multiwfn, which is a method used to distinguish covalent and non-covalent interactions, see Section 4.3.3 for example.
* Composition of AdNDP orbitals can be analyzed. See the example in Section 4.14.3.
* User-defined function 39 is added, which is used to calculate electrostatic potential without contribution of a specific nucleus, and was shown to be useful for studying pKa and interaction energy of hydrogen, halogen and dihydrogen bonds. See corresponding description in Section 2.7.
* User-defined function 38 is added, which is the angle between the second eigenvector of Hessian of electron density and the vector perpendicular to the plane defined by option 4 of main function 1000. In J. Phys. Chem. A, 115, 12512 (2011) this quantity along bond paths was used to reveal π interaction.
IMPROVEMENTS AND CHANGES
* The color of atom spheres in 3D plots now can be adjusted by users. The path of the file recording element color settings is specified by "atmcolorfile" parameter in settings.ini file. See its comment for detail.
* The NBO plot files outputted by NBO 6 are supported.

Multiwfn Version 3.3.4 (Release date: 2014-Jun-9)
IMPROVEMENTS AND CHANGES
* In Hirshfeld and ADCH population analyses, Hirshfeld orbital composition analysis, Hirshfeld surface analysis and fuzzy atomic space analysis module, one can directly select to use the built-in atomic densities (available from H~Lr) to generate Hirshfeld weight. That means it not compulsory to manually prepare atom .wfn files or invoke Gaussian to calculate them anymore. More detail about the built-in density can be found in Appendix 3 of the manual.
* Option 11 in subfunction 1 of main function 18 has been improved and moved to main function 200 as subfunction 10. This function is able to output electric/magnetic dipole moment integral between all orbitals.
BUG FIXED
* A severe bug of ICSS function (subfunction 4 in main function 200) introduced since version 3.3.1 is fixed.
* A bug in suboption 18 of main function 13 is fixed, the curve in X direction is incorrect. Thanks to Tsuyuki Masafumi for pointing out this bug.
* The crash problem of Wiberg bond order for open-shell system is fixed.

Multiwfn Version 3.3.3 (Release date: 2014-May-21)
NEW FUNCTIONS
* Option -2 is added to main function 9 (bond order analysis module). Contrary to traditional implementation of multi-center bond order, this option calculates multi-center bond order based on natural atomic orbital basis. This calculation manner significantly diminished basis-set dependency of multi-center bond order. See Section 3.11.2 of the manual for detail.
* Option 2 of main function 100 now can be used to output present waveufunction to .molden input file.
* Transition magnetic dipole moment density now can be visualized by option 1 of main function 18, see the last part of Section 4.18.1 of the manual for example and theory 5 of Section 3.21.1.1 for introduction.
IMPROVEMENTS AND CHANGES
* Optimized CP searching parameter of topology analysis module to reduce the possibility of missing CPs when CPs are very far from atoms.
* With the help of cubegen, the speed of quantitative molecular surface analysis for ESP can be improved significantly and thus this function can be applied to much larger systems now. See Section 4.12.7 for example.
* A new parameter "iplaneextdata" is added to settings.ini. If is set to 1, then during plotting plane map (main function 4), the data will be directly loaded from a plain text file provided by user.
* Two new real space function, electron linear momentum density in 3D representation and magnetic dipole moment density are supported as the 71~74th and 75~78th user-defined functions, respectively, see corresponding description in Section 2.7.
* Option -2 is added to CDA module, which is used to switch the output destination (screen or plain text file) of CDA results.
BUG FIXED
* Fixed the output bug of option 1 and 2 in function 5 of main function 18.
* In somes cases the ECDA result in CDA module is evidently incorrect.

Multiwfn Version 3.3.2 (Release date: 2014-May-12)
NEW FUNCTIONS
* New options 5 and 6 are added to subfunction 1 of main function 18. By the former, one can obtain contribution from basis functions and atoms to total transition dipole moment; while by the latter one can obtain atomic transition charges.Mulliken partition is employed to derive the quantities. See corresponding introduction in Section 3.21.1 of the manual.
* Subfunction 5 of main function 18 (electron excitation analysis module) now supports plain text file as input, that means non-Gaussian users can also use this function to produce transition dipole moments between all excited states. See Section 3.21.5 of the manual for detail. Meantime, a small bug in this subfunction is fixed.
* In the DOS plotting module (main function 10), up to 10 fragments now can be simultaneously defined, and their colors can be customized, see Section 4.10 for illustration.
IMPROVEMENTS AND CHANGES
* In option 26 of main function 6, orbital occupation numbers now can be set in a more flexible way.
BUG FIXED
* Fixed a severe bug in basin analysis, in some cases the calculation range of grid data is not correct!

Multiwfn Version 3.3.1 (First release: 2014-Apr-25 Last update: 2014-Apr-26)
* Subfunction 8 is added to main function 200, which is used calculate polarizability and 1st/2nd/3rd hyperpolarizability by sum-over-states (SOS) method based on CIS/TDHF/TDDFT calculation, see Section 3.200.8 of the manual for detail and Section 4.200.8 for example
* Subfunction 8 is added to main function 200, which is used to calculate average contact distance between two elements and average coordinate number. This function is very useful for analyzing structure character of atom clusters, see Section 3.200.8 of the manual for detail.
* Some minor improvements and bug fixes.

Multiwfn Version 3.3 (Release date: 2014-Apr-14)
NEW FUNCTIONS
* Subfunction 20 is added to main function 100. This new function is used to parse the output of (hyper)polarizability task of Gaussian09 and then print them in a much more readable format, and at the same time some quantities relating to (hyper)polarizability analysis will be outputted. See Section 3.100.20 of the manual for detail.
* Subfunction 19 is added to main function 100, which can generate promolecular .wfn file based on fragment wavefunctions, see Section 3.100.19 for introduction and Section 4.100.19 for illustrative examples.
* Fingerprint plot analysis (defined in the framework of Hirshfeld surface analysis) is fully supported in main function 12. See Section 4.12.6 for example and Section 3.15.5 for introduction. This function is very useful for analyzing non-covalent interaction in molecular crystal.
* Subfunction 6 is added to main function 200, which is used to analyze correspondence between orbitals in two wavefunctions. See Section 3.200.6 for introduction and example. By this function for example you can know the conversion relationship between the MOs calculated at HF/6-31G* level and that calculated at B3LYP/cc-pVTZ level, or obtain the knowledge about how the MOs produced by HF are related to the natural orbitals produced by post-HF methods.
* Promolecular approximation of reduced density gradient (RDG) and sign(lambda2)rho now supports all elements from H to Rn (in older versions this feature only supports H~Ar).
* In the spectrum plot module (main function 11), the contribution of individual transitions to the total spectrum can be outputted by option 15, this feature is particularly useful for identifying the nature of total spectrum. See Section 4.11.2 of the manual for example. In the meantime, option 16 is added, which is used to locate the positions of minima and maxima of the spectrum.
* Subfunction 5 is added into main function 18, which is used to calculate transition dipole moments between all excited states. See Section 3.21.5 of the manual for detail.
IMPROVEMENTS AND CHANGES
* The charge decomposition analysis (CDA) module now supports .fch and .molden file as input.
* The function for plotting DOS now supports .molden file as input.
* After performing Wiberg bond order analysis, program will not exit.
* When outputting AdNDP orbitals to cube file, the number of grids can be directly set.
* A new parameter "iatmlabtype" is added into settings.ini, which determines if show atom indices when showing atom labels in plane map.
* Fragment can be defined in the Becke and Hirshfeld composition analysis functions.
* A utility used to calculate ring area and perimeter is added to main function 100 as subfunction 25. See Section 3.100.25 of the manual for detail.
* A new parameter "inowhiteblack" is added to settings.ini file. If it is set to 1, then when plotting color-filled map, the regions with value larger and lower than upper limit and lower limit of color scale will not be shown as white and black, respectively.
* A new parameter "bondRGB" is added to settings.ini file, which controls the color of the bonds to be plotted.
* Subfunction -2 and 20 in main function 100 are merged into subfunction 2.
* A parameter "iALIEdecomp" is introduced to settings.ini. When it is set to 1, in main function 1, not only the total ALIE value but also the contribution from each occupied MOs will also be outputted.
* The .wfn file containing g type of GTFs outputted by Gaussian09 since B.01 is supported.
* Main function 11 is improved in many aspects. Rotatory strengths in velocity representation can be loaded from Gausisan output file when plotting ECD spectrum.
* The default color of atomic label is changed, and the color now can be customized by a new parameter "atmlabRGB" in settings.ini.
* The setting of axes in many kinds of plots are improved.
* Phase-space-defined Fisher information density (PS-FID) is supported as 70# user defined function, which has very similar characters to ELF and LOL, the spatial localization of electron pairs can be clearly revealed. See DOI: 10.1016/j.chemphys.2014.03.006 for introduction and illustrative applications.
* A new real space function eta=abs(lambda_3)/lambda_1, which is similar to bond ellipicity and defined in Angew. Chem. Int. Ed., 53, 2766, is supported as the 31# user defined function.
* In topology analysis module, by suboption 7 in option -5, variation of real space function along topology paths can be directly plotted as curve map.
BUG FIXED
* Fixed severe bugs in subfunction 7 and 8 of main function 100, which lead to crash of program.

Multiwfn Version 3.2.1 (First release: 2013-Dec-30, last update: 2014-Jan-8)
NEW FUNCTIONS
* Hirshfeld surface analysis (see e.g. CrystEngComm,11,19) and Becke surface analysis are supported by quantitative molecular surface analysis module, they are introduced in Section 3.15.5 of the manual, a example is given in Section 4.12.5.
* Iso-chemical shielding surface (ICSS) now can be calculated by subfunction 4 of main function 200, see Section 3.200.4 for explanation and 4.200.4 for example.
* In subfunction 1 of electron excitation analysis module, RMSDs of electron and hole can be calculated, which measures their distribution breadth. H index and t index can also be calculated, the latter one is able to reveal whether hole and electron distributions are separated clearly. See introduction in Section 3.21.1 for detail.
* Radial distribution function for any real space function now can be plotted by function 5 in main function 200. See Sections 3.200.5 and 4.200.5 of the manual for introduction and example, respectively.
IMPROVEMENTS AND CHANGES
* In the analysis of the .wfn/.fch/.molden file involving pseudopotential, inner-core electon density can be represented by the EDF information recorded in atom .wfx file produced by G09, see Section 5.7 for detail.
* When plotting IR spectrum in main function 11, the anharmonic frequencies and intensities outputted by G09 D.01 can be parsed.
* After the AIM basins were integrated via option 7 in basin analysis module, the basin volumes with rho>0.001 will be shown, which can be regarded as atomic volume.
* By option 1, quantitative molecular surface analysis module now is able to generate and analyze isosurface of any real space function. In addition, the grid data of real space function can be directly loaded from external .cub/.grd file rather than calculated by Multiwfn internally.
* The rule for locating settings.ini file is changed. In current version, Multiwfn tries to find and use this file in current folder, if it is not presented, the settings.ini in the path defined by "Multiwfnpath" environment variable will be used (if still missing, default settings will be employed instead).
* Deformation density now and be integrated in fuzzy atomic space (via option 1 of fuzzy space analysis module) and AIM basin (via option 7 in basin analysis module).
* User-defined function now supports a lot of LDA and GGA exchange-correlation functionals, such as SVWN5, PBE, BLYP, PW91, B97, HCTH407. Corresponding XC potentials are also available. See the end of Section 2.7 of the manual for detail. In the meantime, Pauli potential is supported (iuserfunc=60), this quantity corresponds to Eq. 16 of Comp. Theor. Chem., 1006, 92-99. Pauli force and Pauli charge are supported as well.
* The default approach used to set up box in basin analysis module has become more reasonable.
* The .wfn file produced by ORCA3.0.1 is now formally supported (although it is non-standard).
* h angular moment of GTF is supported (.fch, .wfx. and .molden can be used).
BUG FIXED
* For certain cases the result of Hirshfeld partition in fuzzy atomic space analysis module is inaccurate, this problem has been fixed.
* Fixed a bug in the calculation of AIM charges when inner-core electrons are represented by EDF field of .wfx file.

Multiwfn Version 3.2 (Release date: 2013-Aug-2)
NEW FUNCTIONS
* Subfunction 10 and 12 of main function 100 have been moved to a newly added main function 18 (Electron excitation analysis) as subfunction 1 and 2, respectively. Subfunction 3 in this main function is completely new and extremely powerful, by which one can (1) Visualize isosurface of hole, electron, overlap of hole-electron, transition density and charge density difference between ground state and excited state (2) Calculate contribution of MO pairs to transition dipole moment (3) Show contribution of each MO to hole and electron distribution (4) Generate and export transition density matrix (5) Export dipole moment integrals between all occupied and all unoccupied MOs. Besides, the coefficients of MO pairs can be very flexibly modified, hence one can investigate e.g. influence of a range of MO pairs on transition density or hole distribution. See Section 3.21.1 of the manual for detail, an example is given in Section 4.18.1.
* By function 4 of main function 18, Δr index can be calculated, which was newly proposed in J. Chem. Theory Comput., 9, 3118. Δr index is used to measure charge-transfer length, and especially useful to diagnose when conventional DFT functional is failure for TDDFT purpose. See Section 3.21.4 for detail and 4.18.1 for example.
* Function 2 is added to main function 200, by this function one can obtain atomic and bond dipole moments in Hilbert space. See Section 3.200.2 of the manual for detail.
* Many new real space functions are supported, including steric potential, steric charge, local electron affinity, Fisher information density, local Mulliken electronegativity, local hardness, integrand of Becke88 and LYP exchange/correlation functional and so on. please check part 100 of Section 2.6 of the manual for detail. These functions can be activated by setting "iuserfunc" in settings.ini to corresponding value.
* Option 7 is introduced to basin analysis mode, which is specific for integrating AIM basin by employing mixed uniform grid and atomic-center integration grids. The result is much more accurate than using option 2. At the same time, option 5 is removed.
* Option 8 is introduced to basin analysis mode, which employs mixed uniform grid and atomic-center integration grids to evaluate electric multipole moments in AIM basins, the result is much more accurate than using option 3.
* Function 3 is added to main function 200. By this function, the grid data of multiple orbital wavefunctions can be calculated and exported to a single cube file or separate cube files at the same time.
* Becke partition is supported to calculate orbital composition (function 9 in main function 8).
IMPROVEMENTS AND CHANGES
* The function used to plot orbital interaction diagram in CDA module is improved, by the option "4 Set the rule for connecting and drawing bars", the rule for plotting and connecting orbital bars now can be defined flexibly to get a clearer picture.
* The setting of lightings is adjusted, so that when the viewpoint is rotated to the backside of the system the atoms will not become too dark.
* In the GUI for showing isosurface, an option "Set lighting" is added to the menu of the GUI, by which one can custom the lighting.
* In the quantitative molecular surface analysis module, a new mapped function "Electrostatic potential from atomic charge" can be selected. After selecting which, the atomic charges stored in specific .chg file will be loaded, and then the electrostatic potential on molecular surface will be evaluated based on the atomic charges, which is much faster than evaluating it based on wavefunction. Another newly added mapped function is local electron affinity, which is useful for analyzing nucleophilic attack, see J.Mol.Model.,9,342.
* The option 10 in post-process menu of quantitative molecular surface analysis module is extended, by which one can obtain the closest/farthest distance between the surface and a given point (e.g. if the point is chosen as geometry center, then the farthest distance can be viewed as molecular radius). Besides, the farthest distance between all surface points can be outputted, which can be regarded as a definition of molecular diameter.
* Option 14 is added to spectrum plotting module, which is mainly used to apply frequency scaling factor onto the calculated harmonic frequencies.
* Option 12 is added to the interface used to plot orbital interaction diagram. By this option one can define the value for shifting energies of fragment orbitals or complex orbitals.
* Option 2 of fuzzy atomic space analysis module now can calculate atomic multipole moments up to octopole, see Section 3.18.3 of the manual for detail.
* In the basin analysis module, when the system is symmetric to the Cartesian plane, the grid setting will be slightly and automatically adjusted, so that the distribution of the grids will be symmetric to Cartesian plane.
BUG FIXED
* Fixed a bug in the option used to output composition of complex orbitals in CDA module.
* Fixed a small bug when plain text file or Gaussian output file is used in DOS plotting module.
* Fixed a small bug when loading open-shell molden input file.
* Fixed a bug of calculating ellipticity of electron density.

Multiwfn Version 3.1 (Release date: 2013-May-18)
NEW FUNCTIONS
* Mac OS X version is available since this version
* The code of CDA module has been significantly rewritten, now infinite number of fragments can be defined. An example of analyzing more than two fragments system is given in section 4.16.3 of the manual.
* By newly added option 7 in subfunction -5 of topology analysis module, real space functions can be calculated along topology paths
* Option 11 and 12 are added to post-process interface of quantitative molecular surface analysis module, by which the surface properties on local surface of each atom or user-defined fragment can be obtained. See Section 4.12.3 of the manual for example.
* Via newly added function 1 in main function 200, reduced density gradient method now can be used to analyze weak interaction in fluctuation environment (e.g. molecular dynamics trajectory). The theory was proposed in J. Chem. Theory Comput., 9, 2226. See Section 3.200.1 of the manual for detail.
BUG FIXED
* Fixed a fatal bug introduced in 3.0.1 version, which makes all negative values become zero during output of cube data.

Multiwfn Version 3.0.1 (Release date: 2013-May-5)
NEW FUNCTIONS
* Becke atomic charge (option 10 in main function 7) now is accompanied by atomic dipole moment correction, which will make the Becke charges have better electrostatic potential reproducibility and can exactly reproduce molecular dipole moment. Meanwhile, users are allowed to adjust atomic radii used for calculating Becke charges.
* Orbital overlap matrix in basins now can be outputted by option 6 in basin analysis module.
* Function 23 is added into main function 100, see manual section 3.100.23 for detail. This function is very similar to the function used to fit ESP charge, but the real space function to be fitted is not limited to ESP, for example you can fit average local ionization energy or even Fukui function distributed on molecular surface to atomic values.
* By main function 5, the real space functions for a set of points now can be simultaneously calculated. See the end of Section 3.6 for detail.
* Function 24 is added to main function 100, which is designed to faciliate calculating NICS_ZZ for non-planar system, see Section 3.100.24 for detail.
* Molden input file (.molden) generated by Molpro, deMon2k, ORCA (up to f angular moment) and BDF is supported. See Section 2.5 for detail.
* Function 21 in main function 100 is significantly extended, aside from geometry/mass-weighted center, many data such as moments of inertia tensor, rotational constant, minimum/maximum distance, radius of gyration and so on can be calculated for specific set of atoms, see Section 3.100.21 for detail. "molgeominfo" parameter is removed from settings.ini, since now this function can do the same thing.
IMPROVEMENTS AND CHANGES
* When drawing DOS graph, now by default a vertical dahsed line is drawn to highlight the position of HOMO level. Option 8 is added to the module to switch the unit of X-axis between a.u. and eV. In the post-process menu, option 16 is added to set the texts in the legends.
* The speed of plotting PDOS and OPDOS for large system is significantly improved.
* The format outputted by option 7 at post-process interface of main function 12 is slightly changed, see manual.
* Subfunction 11 to 15 of main function 6 are merged as subfunction 11.
* Some interfaces used to define fragment (main function -3 and -4, as well as option -1 in bond analysis module) become much more easier to use than before.
BUG FIXED
* Some trivial bugs have been fixed, thanks Arne Wagner for reporting.
* When outputting cube file, the values <=1E-99 will be automatically cleaned to avoid format compatibility problem.
* Fixed small bugs in bond order calculation, meanwhile optimized memory usage.

Multiwfn Version 3.0 (First release: 2013-Mar-24 Last update: 2013-Mar-26)
NEW FUNCTIONS
* Basin analysis is supported as main function 17. This function is very powerful, high-efficient and flexible. For any real space function, attractors can be located, and corresponding basins can be generated and integrated. The grid data calculated by other main functions of Multiwfn (e.g. Fukui function, electron density difference) and the data loaded from cube/.grd file can also be used to define the attractors and basins. Attractors and basins can be directly visualized or be exported as .pdb/.cub file. Electronic multipole moments, localization index and delocalization index can be calculated in the generated basins. The theory, algorithm and usage of the basin analysis module are introduced in Section 3.20 of the manual, five practical examples are given in Section 4.17.
IMPROVEMENTS AND CHANGES
* Multi-center bond order analysis (option 2 in main function 9) was extended to up to 10 centers.
* For the users using 64bit Windows system and whose machine has more than 2GB physical memory, now Multiwfn can process larger system without crashing.
* When showing all properties at a point (main function 1 or option 7 in main function 2), the ellipticity of electron density is outputted simultaneously.
* The memory requirement for storing grid data is reduced by as high as 3/4, that means now you can use Multiwfn process much larger grid data.
* (2013-Mar-26 update) function 5 is added to basin analysis module, which uses multi-level refinement method to improve the integration accuracy in the region close to nuclei, and hence very suitable for integrating source function, which varies very fast near nuclei.

Multiwfn Version 2.6.1 (Release date: 2013-Jan-9)
NEW FUNCTIONS
* Function 18 is added to main function 18, which is used to analyze probability of electron transport route in pi-system according to Yoshizawa's formula (Acc.Chem.Res.,45,1612-1621). See Section 3.100.18 for introduction and Section 4.100.18 for example.
* For a planar molecule, by the new option 22 in main function 100, all pi orbitals can be detected, and you can directly set their or all the others' occupation numbers to zero. The purpose of this option is to faciliate analyses of pi-properties (e.g. ELF-pi) of large conjugated system. Users don't need to manually find out pi orbitals by visually checking orbital isosurfaces any more.
* By option 10 in post-process interface of main function 12 (quantitative molecular surface analysis), one can obtain the closest distance between the surface and a nucleus
* Bird aromaticity index (Tetrahedron,41,1409) now can be calculated in function 13 of main function 100. See Section 3.100.13 for introduction and Section 4.100.6 for example.
* Para linear response (PLR) aromaticity index (PCCP,14,3960) now can be calculated by option 9 of fuzzy atomic analysis module (main function 15), see Section 3.18.8 for introduction and Section 4.15.2 for example.
* Multi-center delocalization index can be calculated in fuzzy atomic space by option 11 in main function 15, up to six-centers.
IMPROVEMENTS AND CHANGES
* When output plane data to plain text file in post-process interface of main function 4, the projected points of critical points, topology paths and interbasin paths can be outputted together.
BUG FIXED
* The result of custom operation and deformation/promolecular map of electrostatic potential was incorrect.
* Hessian of ESP and user defined function outputted in main function 1 was not correct.

Multiwfn Version 2.6 (First release: 2012-Nov-6, last update: 2012-Nov-28)
NEW FUNCTIONS
* Charge decomposition analysis (CDA) proposed by Dapprich and Frenking (JPC,99,9352) and extended CDA (JACS,128,278) are supported as main function 16; The CDA implemented in Multiwfn is a generalized version by Tian Lu, which is not only suitable for close-shell and HF/DFT wavefunctions, but also for open-shell and post-HF wavefunctions. Related theory is described in Section 3.19, two examples are given in Section 4.16.
* Orbital interaction diagram can be plotted in main function 16.
* Electronic/vibrational circular dichroism (ECD/VCD) can be plotted in main function 11 now. Gaussian output file and plain text file are supported as input file, see Section 3.13.1 of the manual for explanation.
* Integral curve of grid data in X/Y/Z direction can be calculated and plotted by option 18 in main function 13. See Section 3.16.14 of the manual for explanation. By this function the so-called "charge displacement curve" can be obtained, which is useful in discussion of inter-fragment charge transfer.
IMPROVEMENTS AND CHANGES
* If "iatom_on_contour_far" in settings.ini was set to 1, when drawing plane map, the atoms far away from the defined plane can be shown as labels in light face type at projected position.
* The process of generating atom wavefunction files is revised. If you are favourite to provide atom wavefunction files in "atomwfn" folder, and these files are generated by yourself, please pay much attention to this change and carefully read Section 3.7.3 of the manual.
* Option 5 is added to quantitative molecular surface analysis module. By enabling this option, the values of mapped function on surface vertices will be loaded from external file rather than be calculated by Multiwfn internally.
* Option 21 is added to topology analysis module. By this option, one can calculate curvature of electron density perpendicular to a specific ring plane, this quantity is useful for measuring aromaticity. See Section 3.14.6 of the manual.
* Option 17 in mainfunction 13 is improved, by this function, one can obtain detail statistic data for the points in specific spatial and value range.
BUG FIXED
* Inaccuracy problem in the calculations of Hirshfeld, VDD and ADCH charges are fixed.

Multiwfn Version 2.5.2 (Release date: 2012-Oct-4)
NEW FUNCTIONS
* Intermolecular orbital overlap integral can be calculated by option 15 in main function 100. Gaussian output files are needed as input. See Section 3.100.15 for detail and see Section 4.100.8 for example.
IMPROVEMENTS AND CHANGES
* Pair density can be calculated by setting pairfunctype to 10, 11 or 12, see the end of part 17 of Section 2.6 of the manual for detail.
* The radii used to calculate Becke charge (option 10 in main function 7) is changed to "modified CSD radii" from CSD radii, see the discussion at the end of Section 3.18.0. This change makes Becke charges more reasonable for organic systems.
BUG FIXED
* When .fch file is used, for d,f,g shells, if both Cartesian and spherical-harmonic basis functions present, the result will be incorrect. (e.g. Using 6-31G* to calculate transition metals, by default, Gaussian use Cartesian type d shell and spherical-harmonic type f shell)
* Fixed a crashing problem of the oribtal composition analysis module based on natural atomic orbital, this bug occurs when some linear dependent basis functions are eliminated by Gaussian.
* CHELPG and MK charges for charged system are incorrect.

Multiwfn Version 2.5.1 (Release date: 2012-Sep-21)
NEW FUNCTIONS
* LOLIPOP can be calculated by function 14 in main function 100. This quantity is useful in studying pi-stacking ability of aromatic systems, see Chem. Commun., 48, 9239 and Section 3.100.14 of Multiwfn manual.
* Laplacian bond order can be calculated by option 8 in main function 9 (This is a new bond order definition proposed by Multiwfn developer, the paper describing this bond order will be submitted to journal soon)
IMPROVEMENTS AND CHANGES
* Barycenter of real space function can be computed now, see Section 4.13.5 of the manual.
* The default radii definition for fuzzy analysis module and fuzzy bond order calculation is replaced with "modified CSD radii", see the discussion at the end of Section 3.18.0.
BUG FIXED
* Fixed a small bug which causes NaN in the calculation of modified Mulliken population defined by Bickelhaupt.
* Fixed a crashing problem of AdNDP module when some linear dependent basis functions are eliminated by NBO program.
* Fixed a fatal bug in CHELPG atomic charge calculation

Multiwfn Version 2.5 (Release date: 2012-Aug-1)
NEW FUNCTIONS
* Main function 15 is added. This function focuses on studying total amount of real space functions distributed in fuzzy atomic spaces. The fuzzy atomic spaces defined by Becke and Hirshfeld are available. By this function, integral of selected real space function in atomic spaces or in overlap regions of atomic spaces, atomic multipole moment, atomic overlap matrix (AOM), localization and delocalization index, as well as three very popular aromaticity indices, namely FLU, FLU-pi and PDI can be computed.
* Fuzzy bond order analysis is supported as subfunction 7 in main function 9. This bond order is akin to Mayer bond order in fuzzy atomic space, but strongly insensitive to basis-set.
* HOMA (Harmonic-oscillator model of aromaticity) now can be computed by subfunction 13 of main function 100.
* Real space function 17 has been completely rewritten, exchange-correlation density, correlation hole and correlation factor can be calculated, please consult part 17 of Section 2.6 and Section 4.3.2 of the manual. Correlation hole now can be evaluated at both single-determinant and post-HF wavefunction levels, meanwhile Coulomb and Fermi correlation now can be separately studied.
IMPROVEMENTS AND CHANGES
* All properties of all critical points now can be simultaneously exported to plain text file by function 7 in topology analysis module.
* The syntax to select orbitals in subfunction 26 of main function 6 is changed, see the program prompt
* Numerous trivial improvements
BUG FIXED
* The sign of dipole moment variation outputted by charge transfer analysis module (subfunction 10 in main function 100) now is inverted.
* At nuclear positions, nuclear ESP function will return 1000 (an arbitrarily selected large value) instead of infinity to avoid numerical issues.
* The program crashes when carry out Wiberg bond order analysis for open-shell system.

Multiwfn Version 2.4 (First release: 2012-May-6, latest revision time: 2012-Jun-14)
* Adaptive natural density partitioning (AdNDP) analysis is supported as main function 14, this function is quite useful for analyzing multi-center orbitals. See Section 3.17 and 4.14 of the manual.
* Isosurfaces can be drawn using transparent style (Linux version doesn't support this feature).
* Source function defined by Bader is supported.
* DMol3 .grd file is supported.
* Fixed some small bugs.
2012-May-14 update: Fixed a fatal bug in plotting ESP on a plane when basis-sets containing diffuse functions are used.
2012-Jun-14 update: .xyz format is supported. A small bug during reading NBO plot files is fixed. A fatal bug in calculation of Fermi hole function for .fch file is fixed.

Multiwfn Version 2.3.3 (Release date: 2012-Apr-9)
* Orbital occupancy-perturbed Mayer bond order (namely decomposing Mayer bond-order to orbital contributions) is supported as subfunction 6 in main function 9. Please consult Section 3.11.5 and 4.9.1 of the manual.
* Transition density matrix outputted by Gaussian can be plotted by function 12 in main function 100, this is useful for analyzing spatial span of electron excitation. Please consult Section 3.100.12 and Section 4.100.5 of the manual.
* Two orbital isosurfaces can be shown simultaneously by main function 0, contour map of orbital wavefunctions of two orbitals can be drawn simultaneously by main function 4. Please consult Section 4.0.2 and 4.4.5 of the manual. This update is useful for visually analyzing orbital overlapping of NBOs.
* Isosurfaces can be plotted by more styles now, currently supported styles include: solid face, mesh, points and solid face+mesh.

Multiwfn Version 2.3.2 (Release date: 2012-Mar-27)
* Orbital spin-type recorded in "$MOSPIN $END" field at the end of the wfn file outputted by Molden2aim 2.0.5 is supported
* Fully compatible with the g GTFs in the wfn file outputted by Molden2AIM
* Some bugs in quantitative molecular surface analysis module are fixed, internal charge separation calculated by previous version is found to be incorrect
* Accuracy of calculation of electrostatic potential is improved
* A contour line corresponding to vdW surface (electron density=0.001) can be plotted on contour/gradient line map or vector field map by choosing option 15 in post-process stage
* Fragments can be defined in bond order analysis module by option -1. If two fragments have been defined, when performing Mayer/Wiberg, Mulliken bond order analysis, the total bond order between atoms in fragment 1 and 2 will be printed together

Multiwfn Version 2.3.1 (Release date: 2012-Mar-6)
* Analysis of orbital composition by natural atomic orbital(NAO) approach is supported as subfunction 8 of main funcition 8.
* Critical points and paths can be exported as pdb file, so that they can be conveniently viewed by external visualization softwares such as VMD
* Fixed a fatal problem in the ELF/LOL calculation on post-HF wavefunctions
* Orbital spin-type can be set customly by option 27 in in main function 6
* Many trivial improvements
* Many trivial bugs are fixed

Multiwfn Version 2.3 (Release date: 2012-Feb-18)
* Molecular surface analysis is added as main function 12, which is very useful for predicting strength of molecular interactions, thermodynamic properties, reactive sites, etc. Electrostatic potential and average ionization energy are supported as mapped functions. Surface properties such as surface area, average value and std. of mapped functions can be computed, local minimum and maximum points can be located.
* Gaussian-type cube file is supported. Isosurface can be viewed by main function 0 after loaded a cube file
* GsGrid program has been entirely merged into Multiwfn as a new main function 13. A cube file should be loaded (or use main function 5 to generate a set of grid data) before entering this module. User can perform mathematical operations on grid data, or set value in certain range, or extract data in specified plane.
* Multi-center bonds with large bond order can be automatically searched

Multiwfn Version 2.2.1 revision 1 (Release date: 2011-Dec-15)
* Fixed a bug introduced by version 2.2.1 (that is Multiwfn crashes during reading the .fch files produced by unrestricted calculation with cartesian basis functions)
* Fixed a bug in the interface for selecting the interbasin surfaces to be generated
Multiwfn Version 2.2.1 (Release date: 2011-Dec-3),
* A serious bug in reading the .fch files produced by unrestricted calculation with spherical-harmonic basis functions is solved
* Merz-Kollmann charge is supported in population module
* Option 10 is added to topology analysis module, this is a small tool used to calculate Shannon aromaticity index

Multiwfn Version 2.2 (Release date: 2011-Nov-28)
* A new real space function "Average local ionization energy" is supported
* Linux version is available!
* The function used to calculate molecular VDW volume is improved
* CHELPG method is supported (Option 12 in population analysis module)
* Interbasin surface can be plotted (Option 10 in topology analysis module)
* Interbasin path derived from (3,-1) can be plotted on contour/gradient/vector field map (Option 6 in graph post-process stage)
* Topology analyses for orbital wavefunction, LOL, ELF and laplacian of rho are supported
* A serious bug in calculating ELF/LOL for restricted-open shell system is solved
* Fixed some bugs in reading wfn files
* Option -1 and -2 in main interface have been removed, one can realize the same purpose by setting occupation number of uninterested orbitals to zero via selection 26 and 34 in main function 6.

Multiwfn Version 2.1.2 (Release date: 2011-Sep-2)
* Spherical harmonic gauss functions are supported (both for .fch file and NBO plot files), "6D 10F" keywords in Gaussian route section are not required from now on.
* A serious bug in reading NBO .31 file is detected and solved.
* A new function isd added to main function 100, used to integrate the overlap of the norm of two specified orbitals in whole space.

Multiwfn Version 2.1.1 (Release date: 2011-Jul-16)
* Critical points and paths are allowed to be portrayed on contour/gradient/vector field map. See Section 3.7.4 of the manual.
* The quality of gradient line map is improved, some parameters for drawing gradient lines are controllable now at post-process stage.
* Plane graph type 6 and 7 are combined together. A new plane graph type, namely vector field (with/without contour lines) is supported.
* Multiple contour lines (rather than only one as before) are permitted to be drawn on color-filled map.
* The windows size of GUI is fixed.
* Color and style of positive part and negative part of contour lines can be set by user in "contour line setting" interface.
* A new routine is added used to analyze charge-transfer, see Section 3.17.10 and 3.100.10 of the manual.

Multiwfn Version 2.1 (Release date: 2011-Jun-26)
* Topology analysis for electron density is added (Main function 2)! Critical points and bond paths can be easily and quickly searched and visualized, see Section 3.16 and 4.2 in manual for detail.
* Cutoff for evaluation of exponential function is employed. For large system, calculation speed of grid data is faster than previous several times! The cutoff threshold is controlled by "expcutoff" in settings.ini, the default value is very safe.
* A new function is added to main function 100 used to evaluate coordination number of all atoms.
* In subfunction 1 of main function 100, when real space function 15-13 or 16-14 is selected (these combinations are generally used for weak interaction analysis), about 35% computational cost is reduced.
* The default contour line setting for ELF/LOL has been changed to a more proper one.

Multiwfn Version 2.02 (Release date: 2011-Jun-3)
* In the post-process step of plotting curve map, option 6 is newly added to search for all local minimum and local maximum points, option 7 is newly added to search the X position where Y value equals to given value.
* If the real space function you selected is Fermi hole/correlation factor, the reference point will be marked by blue cross on the contour map alone with atom labels.
* A new atomic charge calculation method ADCH (Atomic dipole corrected Hirshfeld) is added.
* Using IOp(3/32=2) in Gaussian to avoid linear dependency checking is not required again, the .fch file with basis function elimination can be loaded directly now.

Multiwfn Version 2.01
* Fixed some trivial bugs
* Fixed serious bug of generating complex initial guess from fragment wavefunctions
* In some functions the energy labled is eV, but actually should be a.u., this bug has been fixed
* Fragment definition module in orbital composition analysis and DOS has been enhanced
* When "ipolarpara" in settings.ini is set to 1, spin polarization parameter function will be used instead of spin density
* Formulas of ELF and LOL for spin-polarized case were modified, see description of ELF and LOL in manual
* LOL defined by Tsirelson is added, change "ELFLOL_type" in settings.ini to 1 to enable it, then the LOL defined by Becke will be replaced.
* When drawing curve map, a vertical line with specified X coordinate can be added to the graph. The ratio of X-axis and Y-axis length is now adjustable
* Distance criterion for labelling atom in contour and gradient map is adjustable now, see "disshowlabel" in settings.ini
* The method 6 and 7 for defining spatial scope of grid data have been slightly modified

Multiwfn Version 2.0
*加入了Fermi穴/Fermi相关因子函数（限单行列式波函数），参考点通过settings.ini里的refx/refy/refz设置。
*在读取.fch文件时不仅占据轨道被读取，空轨道也被读取，因此可以绘制空轨道图形。
*新支持Gaussian09 B.01开始引入的AIM Extended Wavefunction Files(.wfx)格式，支持Additional Electron Density Function(EDF)以描述ECP计算的内层电子密度，注意所有内层电子密度函数必须写在同一个EDF段落中，且只支持s型拟合函数。
*输入文件名时只需直接输入字母o就可以读取上次输入的文件，免得分析同一个分子时每次都要输入路径。
*在功能7里面新加入Mulliken布居和Lowdin布居，可以获得每个基函数、壳层的布居数，也可以获得每个分子轨道对原子、基函数布居数的贡献。加入了Ros & Schuit(亦称SCPA)、Stout & Politzer、Bickelhaupt分别提出的三种修改的Mulliken布居方法(MMPA)。这些方法必须以.fch作为输入。另外还增加了Becke空间划分的布居方法。
*新增主功能8用于轨道成分分析，可以分析每个基函数、壳层、原子的贡献。可以自定义片段以获取片段对轨道的贡献，还可以获得每个轨道中两个片段之间交叉项的成分。这些功能必须以.fch作为输入，允许用球谐型高斯函数，但需要同时读取用了iop(3/33=1)的Gaussian输出文件。主功能8也包含通过Hirshfeld方法计算轨道中各个原子成分的功能，输入文件不限于.fch文件。
*新增主功能9用于键级分析（必须以.fch作为输入），包括双、多中心Mayer键级分析、Lowdin正交化基函数下的Wiberg键级分析、广义化Wiberg键级分析、Mulliken键级分析及轨道贡献分解。
*新增主功能10，用于绘制Density-of-states(DOS)、Partial DOS(PDOS)、Overlap population DOS(OPDOS，亦称COOP)。支持Gaussian、Lorentizan、Pseudo-Voigt展宽，可自定义展宽参数，可导出数据。需要用.fch或者Gaussian用pop=full的输出文件或者记录了能级信息的文本文件作为输入。
*新增功能11，用于从Gaussian输出文件或者自行编写的文本文件中读取数据来绘制IR/Raman/UV-Vis光谱图，各个峰展宽方式、半高宽等参数可自定义。
*功能100里加入了计算alpha和beta轨道波函数间的重叠积分矩阵功能。加入了监视SCF收敛趋势的功能。加入了从使用pop=full的Gaussian输出文件中生成含有初猜信息的Gaussian输入文件功能。加入了通过片段波函数构建整体初猜波函数的功能。
*Gaussian程序路径不再通过gaupath.txt定义，而是改成写在settings.ini里的gaupath里。
*修改了输出wfn文件的模块，通过功能-3或-4删掉一部分不感兴趣的原子及其基函数后，用功能6的功能0保存出的wfn文件将不包含它们的信息，并可被AIM2000等程序正常读取，可用于减少在这些程序中的运算时间。
*生成格点文件、预览轨道、计算平面及直线上的数据等功能通过OpenMP被并行化，计算速度在多CPU核心计算机上有质的飞跃！用户需将settings.ini里的nthreads设成当前计算机的CPU核心数。
*改进了第三主族元素球对称化电子密度的方法，正式支持计算第一过渡金属元素的变形/Promolecular密度属性（即目前可以完整支持计算前四周期元素的变形密度属性）。

Multiwfn Version 1.5 (Release date: 2010-Oct-2)
*加入对NBO程序产生的plot文件的支持。载入.31文件后，再载入.32至.40文件中的一个（依次对应PNAO/NAO/PNHO/NHO/PNBO/NBO/PNLMO/NLMO/MO），就可以绘制相应类型的轨道。
*在显示等值面时可以选择是否同时显示分子结构和原子标签，并能够显示格点数据涉及的空间范围。
*在修改波函数（功能6）里面添加两个新的功能，即平移体系和平移并复制体系功能，由此可以将Gaussian周期性计算获得的单胞的波函数延展成周期性体系波函数。
*在绘制等值线时允许同时加粗多条线。
*新增了settings.ini文件，应放在调用Multiwfn可执行文件的目录下。文件包含了Multiwfn要用的各种参数，可由用户根据注释自行修改来控制Multiwfn在计算、绘图、输出等方面的细节设定。
{"*新增了Reduced density gradient(RDG)函数、Sign(lambda2)*rho函数，以及它们在Promolecule密度近似下的函数。还新增了用户自定义函数，可以根据实际需要自行编写内容以扩展Multiwfn的功能。"}
*丰富了格点运算时的网格设定功能，变得更为方便、智能化。
*增加功能10，包含一些实用工具。现包括四个子功能：
1 做空间格点上任意函数 vs. 任意函数的散点图并生成它们的格点文件。
2 将当前分子结构保存为pdb文件。
3 根据原子范德华半径用蒙特卡罗法计算分子范德华体积。
4 对指定函数在全空间进行积分。
*新支持读入pdb文件，主要作为计算Promolecule近似下的RDG函数的分子结构输入，结合功能0亦可将Multiwfn作为分子结构可视化程序。
*以.fch作为波函数输入时，允许的基组中最高角动量函数由f增加到g，.31文件作为输入时也支持到g函数。
*自定义运算得到的属性（包括Promolecule、变形属性）已允许绘制梯度线图。
*在功能0的图形界面中加入了轨道波函数等值面预览功能，大大简化了观看轨道图形的步骤。

Multiwfn Version 1.4 (Release date: 2010-Jul-8)
*加入核静电势函数，哈密顿动能函数K(r)，拉格朗日动能函数G(r)，电子定域化函数(ELF)，定域化轨道标识函数(LOL)，Shanon信息熵函数。正式加入静电势属性，可以像其它属性一样直接进行作图、生成格点文件等操作，并将功能2融合进了功能1，也就是使用功能1显示某一点属性时就会显示此点静电势数值。
*可以读入含有原子电荷及坐标的.chg文件计算、显示静电势，详见实例。
*对主功能3,4,5增加了子功能-10，用户可以自定义在绘制图形或生成格点文件时坐标范围由分子尺寸往外延展的距离。
*改进了计算各种属性的算法，节省了内存并且计算速度增加十分明显，且并不因此损失精度。比如计算拉普拉斯值格点文件比1.3版快了一倍。
*调整等值线设定界面中可以根据等差数列、等比数列生成一批等值线；可以使某个等值线在绘图时加粗；在绘制填色图时允许同时绘制一条等值线。
*调整了用功能4作图后各选项显示的顺序，增加了设定X,Y轴上数值标签数目、设定标签之间ticks数目、设定ticks朝向的功能。第4、5种绘图类型可以允许不显示网格线，第4种图形还允许输入色彩刻度上下限改变着色的颜色。
*修正、改进显示分子结构时对是否成键的判断方法。修正使用赝势波函数时输出的cube文件原子序号存在的错误及其它使用赝势时出现的问题。修正不能读取不含SP壳层的fch文件的bug。对一些细节进行了修改，如互换了输出格点文件和显示等值面的顺序，避免在观看等值面前需等待格点文件写入硬盘。
*给显示分子结构、地形图、等值面的窗口增加了GUI界面，可以方便地旋转、缩放，以及调整成键判据、原子标签大小、调整等值面数值等。

Multiwfn Version 1.3 (Release date: 2010-Apr-24)
*允许用户自定义运算操作得到平面图，操作包括加减乘除，而不仅仅限于差值平面图。
*加入了自定义运算操作得到曲线图及格点文件的功能，如计算电子密度差格点文件。
*可以将等值线的数值的设定保存到文件，也可以从文件读取等值线设定。
*输出静电势时将总静电势和电子静电势分别输出。
*输出格点文件后显示最大、最小值的位置。
*计算电子密度梯度和二阶导数改为了解析形式，速度较原先分别提升了至少一倍和三倍，且增加了精度。
*加入了计算某个片段对结果的贡献功能，即功能-3；也允许指定不计算哪些片段的贡献，即功能-4。
*可以直接计算promolecule属性和差值属性，避免了需要手动依次生成每个原子wfn文件并在multiwfn中设定操作的麻烦。
*加入功能7用于电荷布居分析，目前包括几种空间划分的方法，即Hirshfeld电荷、VDD电荷、积分voronoi胞内电子密度、积分Rousseau修改的voronoi胞内电子密度（可能不准确），并可输出原子偶极矩。
*对功能6进行了扩充，增加了设定某高斯函数属性功能。通过子功能12，可以方便地批量修改特定类型的高斯函数在某些MO上的展开系数。
1.3.1 Release date: 2010-APR-25
修正了一个计算原子wfn后可能自动退出的bug。
1.3.2 Release date: 2010-May-10
修正了生成原子.gjf文件时用户输入的基组未生效的bug（导致.gjf中基组为空白）。增加允许用户自行设定计算原子波函数方法的设置。

Multiwfn Version 1.2 (Release date: 2010-Feb-9)
*加入了对10f型轨道的支持。
*新支持非限制性Post-HF波函数用以计算自旋密度。
*新增加直接读入高斯03/09的fch文件的支持，可以观看NBO轨道。
*绘制平面图时允许通过输入三个点坐标定义平面，允许自定义平面的原点与平移向量。
*任何方式定义平面均可显示原子符号。
*增加了silent模式便于批量执行，silent模式见readme第6部分的说明。
*绘制曲线图允许用户自定义Y轴的上下限。
*加入了绘制差值图的功能。

Multiwfn Version 1.1 (Release date: 2010-Jan-17)
对1.0的功能进行了诸多重要的扩充

Multiwfn Version 1.0 (Release date: 2009-Nov-27)
最初发布。