Please check this page frequently, because Multiwfn is always in active development! Only recent updates are shown here. To check full update history since the first release (Nov, 2009), please click: all_updates.html

- [2020-Oct-30] Pipek-Mezey orbital localization now supports carrying out based on Becke population. It can be selected by option -6 in main function 19. Result of this method is similar with Pipek-Mezey localization based on Mulliken or Lowdin population, but fully compatible with diffuse functions. See Section 3.21 of manual for more information.
- [2020-Oct-31] A general module for evaluating orbital energies is available as subfunction 6 of main function 300. In this module, one can load Fock/KS matrix from an external file, then the energies of the orbitals in memory will be calculated as expectation of the Fock/KS operator. See Section 3.300.6 of Multiwfn for detail, and see Secton 4.300.6 on illustration of using this module to evaluate energies of natural transition orbitals (NTO).
- [2020-Nov-28] BOD and NAdO analyses now can be used to analyze interaction between two specific fragments to gain deep insight into their interaction, see Section 4.200.20.3 of manual for example.
- [2020-Dec-11] In the function of decomposing Wiberg bond order as NAO pair contribution, now user is allowed to define two fragments, then NAO shell interactions between the two fragments will be given. See updated Section 4.9.4 for example.
- [2021-Jan-10] A set of geometry operation functions have been collectively added as subfunction 7 of main function 300. Functions: Translate selected atoms, make center of selected atoms at origin, rotate selected atoms around a Cartesian axis or a bond, make a bond parallel to a Cartesian axis, make electric dipole moment parallel to a Cartesian axis, mirror invert, generate randomly displaced geometries, etc. See Section 3.300.7 for introduction of this new module.
- [2021-Jan-23 ~ 2021-Feb-8]
**(VERY IMPORTANT)**Many wavefunction analyses for periodic systems based on .molden file generated by CP2K program have been supported, see Section 2.9.2 of Multiwfn manual for detail. For example, Multiwfn is able to easily perform RDG(NCI) analysis, calculate Mayer bond order, calculate CM5 charge for periodic systems. - [2021-Jan-30]
**(IMPORTANT)**Averaged independent gradient model (aIGM) analysis proposed by Tian Lu has been supported as subfunction 12 of main function 20. See Section 3.23.9 for introduction. aIGM is an extension of IGM to fluctuation environment, it can nicely reveal averaged interaction during molecular dynamics simulation. - [2021-Feb-5] Molecular surface distance projection map now can be plotted by subfunction 8 of main function 300, see Section 3.300.8 of manual for introduction and Section 4.300.8 for example. This map is very useful in graphically characterizing molecular structure and identifying possible steric effect.
- [2021-Feb-10] CP2K input file now can be generated via subfunction 2 of main function 100 (it can also be entered by inputting
*cp2k*in main menu). This function is quite flexible and convenient. To use this function, usually you should load a file containing geometry and cell information, see Section 2.9.3 of manual for detail. - [2021-Mar-29]
**(IMPORTANT)**Calculating IFCT terms for a batch of excited states and then plotting charge-transfer spectrum (proposed by me in*Carbon*, 187, 78 (2022)) is supported by Multiwfn. This is extremely useful for unveiling nature of UV-Vis spectrum. See Section 3.21.16 for introduction and Section 4.18.16 for example. - [2021-Apr-24] Input file for uESE/xESE code (http://iqcc.udg.edu/~vybo/ESE/) now can be directly generated. See end of Section 3.9.14 of Multiwfn manual for detail. uESE and xESE are new solvation models for accurately evaluating solvation energies, they perform notably better than the very popular SMD model for ionic and neutral solutes, respectively.
- [2021-May-5] Atomic effective volumes in a molecule and atomic free volume now can be calculated by Fuzzy analysis module under various fuzzy partitions. These volumes have been employed for estimating atomic C6 dispersion coefficients, see Section 3.18.12 of manual for detail about this new function, example is provided in Section 4.15.4.
- [2021-May-6] The method proposed in J. Comput. Chem.,
**37**, 2279 (2016) has been supported in subfunction 16 of main function 100 to calculate various quantities defined in the framework of conceptual density functional theory when HOMO and/or LUMO are (quasi-)degenerate. See Section 3.100.16.4 of manual for introduction and Section 4.100.16.3 for example. - [2021-May-8] A new option "Export all internal coordinates" has been added to "Tools" drop-down box in the menu of main function 0. It can export all bonds, angles and dihedrals of present system to int_coord.txt in current folder.
- [2021-May-14] Subfunction 7 of main function 300 newly supports three new subfunctions: (1) Reorder atoms according to various rules (2) Making longest axis parallel to a vector or Cartesian axis (3) For molecular crystals, making molecules truncated by cell boundary as whole molecules.
- [2021-Jun-3] Atomic polarizability using Tkatchenko-Scheffler method can also be calculated, see Section 3.18.12 for introduction and Section 4.15.4 for example.
- [2021-Jun-21] Nucleophilic and electrophilic superdelocalizabilities proposed by Schüürmann in
*Environ. Toxicof. Chem.*,**9**, 417 (1990) now can be calculated by option 8 of subfunction 16 of main function 100. They are useful as molecular descriptors for building QSAR relationship. The implementation in Multiwfn is slightly different to the original one, see Section 3.100.16.5 of Multiwfn manual for detail. - [2021-Jun-27 & Aug-11]
**(IMPORTANT)**Molecular planarity parameter (MPP) and span of deviation from plane (SDP) now can be calculated. They are rigorous, meaningful, and universal metrics of molecular planarity. In addition, relative position of atoms with respect to the fitting plane can be colored for intuitive visualization. See my paper J. Mol. Model., 27, 263 (2021) DOI: 10.1007/s00894-021-04884-0 for detailed description of these novel methods of quantifying and visualizing molecular planarity. Brief introduction is given in Section 3.100.21 of manual, calculation example is given in Section 4.100.21.2. - [2021-Jul-15] Subfunction 17 has been added to main function 100. It is used to generate Fock/KS matrix based on orbital energies and expansion coefficients of input file, then the matrix can be exported as plain text file. See Section 3.100.17 of manual for detail.
- [2021-Jul-25]
**(VERY IMPORTANT)**Extended Transition State - Natural Orbitals for Chemical Valence (ETS-NOCV) has been supported! This is a popular and quite useful method that can provide deep insight into orbital interactions. See Section 3.26 of manual for detailed introduction of this analysis and Section 4.23 for rich examples of applying ETS-NOCV on studying various kinds of interactions. - [2021-Jul-10&2021-Sep-1] Electric hexadecapole moment and electronic spatial extent <r^2> now can also be evaluated analytically by subfunction 5 of main function 300.
- [2021-Oct-30] Labels of ELF basins (such as C(F1), V(O4), V(Li2,Li3,Li5), etc.) can be automatically assigned by new option 12 in basin analysis module when the real space function used to partition the basin is ELF. See updated Section 4.17.2 of manual for example of using this option. This option is particularly useful when you employ ELF to conduct bond evolution theory (BET) analysis, in which you need to assign basin labels for many structures in IRC path.
- [2021-Nov-3] Relative Shannon entropy density has been supported as user-defined function 49, generation of promolecular wavefunction is needed before using it, see corresponding part of Section 2.7 of manual for detail. Its analytic gradient and Hessian are also available, so topology analysis for it via main function 2 can be conducted accurately and efficiently.
- [2021-Nov-19] Subfunction 7 of main function 300 newly supports two new subfunctions: "Translate system along cell axes by given distances" and "Translate system to center selected part in the cell".
- [2021-Dec-22] Plotting promolecular and deformation properties using main functions 3, 4 and 5 have been supported for periodic systems.
- [2022-Jan-12] Local Hartree-Fock exchange energy (Hartree-Fock exchange energy density) has been supported as the 999th user-defined function, see corresponding part in Section 2.7 of Multiwfn manual for detail.
- [2022-Feb-14] UV-Vis spectrum plotting function (main function 11) has supported CP2K TDDFPT output file.
- [2022-Feb-14]
**(IMPORTANT)**Hole-electron analysis and NTO analysis have fully supported CP2K for characterizing electronic excitation of periodic systems. Just use .molden file containing all occupied and virtual orbitals as well as the TDDFPT output file as input file. See Section 3.21.A on how to prepare the file. - [2022-Feb-17] Option 25 has been added to subfunction 7 of main function 300. If you load a crystal system in Multiwfn, you can use this option to very easily extract a cluster containing a selected molecule and a shell of neighouring molecules, see updated Section 4.12.6 of manual for example. This cluster model can be used in IGMH analysis, Hirshfeld surface analysis, and so on for visually studying weak interaction in molecular crystal.
- [2022-Feb-25] Subfunction 19 of main function 100 has been significantly rewritten and improved. Now it can be used to generate wavefunction file (.wfn or .mwfn) based on fragment wavefunction files in any format.
- [2022-Mar-8] Scripts for automatically invoking ORCA and Multiwfn to extremely easily calculate RESP, RESP2 and 1.2*CM5 atomic charges are provided. Please search RESP_ORCA.sh, RESP2_ORCA.sh and 1.2CM5_ORCA.sh in Multiwfn manual for detail.
- [2022-Mar-18] Plane-averaged curve can be calculated and plotted based on loaded grid data by subfunction 18 of main function 13.
- [2022-Apr-13] Subfunction 5 of main function 18 now is able to calculate transition magnetic dipole moment between ground state and excited states, as well as among various excited states. See Section 3.21.5 of Multiwfn manual for detail.
- [2022-Apr-19] Atomic dipole moments and quadrupole moments calculated by Multiwfn now can be very easily and intuitively visualized in VMD program via a script provided in Multiwfn package, this is important for studying anisotropic distribution of electron density within atomic space. See introduction and example in Section 4.15.5 for detail.
- [2022-May-14] The USI (ultra-strong interaction) index and BNI (bonding and noncovalent interaction) index proposed in J. Phys. Chem. A, 126, 2437−2444 (2022) has been added as user-defined functions 819 and 820 respectively. They are new tools for studying chemical bonds.
- [2022-Jun-11] New option "9 Multiply all grid data by Hirshfeld weights of a fragment" has been added to post-processing menu of main function 5, which can be used to only make isosurface around interested fragment visible.
- [2022-Jun-25] Diameter of cavity of molecules and crystals now can be easily and accurately calculated, and they can be graphically illustrated. See Section 4.100.21.4 of manual for example.
- [2022-Jun-16] Directional UV-Vis spectrum now can be plotted, which greatly helps to understand intrinsic nature of optical absorption of systems with clear anisotropic character.
- [2022-Nov-21] Spatial delocalization index (SDI) now can be calculated, it is able to character spatial delocalization extent of any real space function, and can quantify orbital delocalization character like ODI. see Section 3.200.19 of manual for detail and Section 4.200.19 example.
- [2023-Jan-16] Spectrum plotting module (main function 11) now can plot NMR spectrum for CP2K based on .data file generated by NMR task. See Section 3.13.5 of manual for detail.
- [2023-Jan-21] Spectrum plotting module (main function 11) now can plot Raman spectrum for CP2K based on output file of vibrational analysis task. See Section 3.13.2 of manual for detail.

- [2020-Aug-21] "gbw2chk.sh" script has been added to "examples\scripts folder", it is used to convert all ORCA .gbw files to .chk file of Gaussian with same name, so that Gaussian can use converged wavefunction of ORCA as initial guess. The ORCA, Multiwfn and Gaussian must have been installed on local machine. The "chk2gbw.sh" works similarly but for .chk->.gbw conversion.
- [2020-Sep-11]
**(IMPORTANT)**Multicenter bond order (MCBO, also known as multicenter bond index) calculation function has been significantly improved!!!!! Due to implementation of the new algorithm developed by Tian Lu, the cost for large rings has been reduced by several orders of magnitude, and the cost now grows only linearly with the number of ring members, hence one can very quickly calculate MCBO for a ring consisting of even dozens of atoms! In addition, the upper limit of ring members has been removed. - [2020-Sep-12] Even after using some analysis functions involving real space functions (e.g. main functions 2, 4, 5, 7, 9, 12, 17...), all virtual orbitals will still be retained when you use input file containing basis function information. (In old versions, virtual MOs higher than LUMO+10 are automatically removed after using these functions)
- [2020-Sep-14] Calculation speed of IGMH analysis has been significantly improved when .fch/.molden/.gms file is used as input file.
- [2020-Sep-17&20] Algorithm of LOLIPOP module becomes more reasonable, the result is thus slightly different to older versions. In addition, option 6 is added to this module to export the actually considered points to pt.xyz file so that user can then use VMD to visualize distribution of the points. Option 5 is also added, by which user can select which side of the ring will be considered in the LOLIPOP calculation. New LOLIPOP example has been added to Section 4.100.14 of manual to illustrate the new features.
- [2020-Oct-14] In the conceptual density functional theory module (subfunction 16 of main function 100), after selecting option 2 or 3, if N/N-1/N+1.wfn cannot be found in current folder, user will be asked to input path of wfn/wfx/fch/mwfn file of corresponding state (older version can only use .wfn file in current folder).
- [2020-Oct-14] In the orbital localization module and biorthogonalization module, if orbital energy is needed to calculate, in the step of loading Fock matrix, now one can ask Multiwfn to directly load it from ORCA output file. The keyword "%output Print[P_Iter_F] 1 end" must be specified in the ORCA input file to request ORCA to print Fock matrix at each SCF iteration.
- [2020-Nov-6] AdNDP module, subfunction 16 of main function 200, and subfunction 13 of main function 18, now export the newly generated orbitals in .mwfn format instead of .molden format, since .mwfn format has evident advantages.
- [2020-Dec-2] Contour line map now can be filled by colors between the lines, one can obtain very pretty map using this new drawing style. User should normally draw contour line map via main function 4, then select option 9 in the post-processing menu. See updated Section 4.4.9 of manual for illustration.
- [2020-Dec-8] A few potentials of kinetic energy funtionals have been supported as user-defined function 1210, see Section 2.7 for detail.
- [2020-Dec-11] In option 15 of main function 11 (plotting spectrum), one can input 0 and then input a X position, then 10 transitions having largest contribution to this position will be shown, This is quite convenient to make clear major contributors at specific spectrum positions (e.g. peak positions of important absorptions). See updated Section 4.11.2 for example.
- [2020-Dec-22] IRI (Interaction region indicator) analysis has adopted a new form of IRI function, whose graphical effect is better. The corresponding VMD plotting script is also updated. Hence the result is marginally different to version 3.7.
- [2020-Dec-23] In the spectrum plotting module, the option "17 Other plotting settings" has been significantly extended, in which one can set number of decimal places in axes, set type of labels (float, exponent, scientific), set text size of axis name / ticks / legends, and set position of legends.
- [2020-Dec-25] The subfunction 11 of main function 18 now is able to decompose transition electric dipole moment between two excited states into contributions from various basis functions and atoms, see Section 3.21.11 of manual.
- [2021-Jan-1] Calculation speed of orbital-weighted Fukui function and dual descriptor has been significantly improved.
- [2021-Jan-10] "ibasinlocmin" parameter has been added to settings.ini. During generation of basins in main function 17, when grid data is found to be non-negative everywhere, minima (repulsors) will be located instead of maxima (attractors)
- [2021-Jan-10] Text size of ticks, axis name and legend in DOS plotting module now can be set by option 21 of post-process menu.
- [2021-Jan-14]
**(IMPORTANT)**d-band center now can be calculated via DOS plotting module, it is a very popular quantity in studying chemisorption of molecule on transition metal surface. See Section 4.10.6 for example on how to calculate it. - [2021-Jan-15] Center positions of positive charges (nuclear charges) and negative charges (electronic charges) are printed by subfunction 5 of main function 300.
- [2021-Jan-16] Barzilai-Borwein steep descent algorithm has been supported in topology analysis module, it is a robust algorithm dedicated to search minima for any real space function. It can be activated using suboption 12 of option -1 in topology analysis module.
- [2021-Jan-28] A fully automatic shell script for calculating 1.2*CM5 charges based on Gaussian and Multiwfn is provided and described in Section 4.7.9. 1.2*CM5 is a charge model well compatible with OPLS-AA forcefield, see J. Phys. Chem. B, 121, 3864 (2017).
- [2021-Jan-29] Energy decomposition analysis based on molecular forcefield (EDA-FF) now can be employed to arbitrarily large systems since the excessive memory consuming for storing huge matrices has been fully avoided.
- [2021-Jan-31] The functions for processing grid data (main function 13) have been fully compatible with non-orthogonal grid.
- [2021-Feb-3] Suboption 4 has been added to option -4 of basin analysis module (main function 17). This new option is used to export all atoms and attractors to a .gjf file, which can be loaded into GaussView, this feature makes visualization of attractors very convenient. See end of Section 4.17.2 for detail.
- [2021-Feb-4] CP2K input file now can be loaded to provide atom information and cell information.
- [2021-Feb-10] Quantum ESPRESSO input file now can be created via option 26 of subfunction 2 of main function 100.
- [2021-Feb-14]
**(IMPORTANT)**.cif file now can be loaded to provide atom information and cell information. - [2021-Feb-20] δg
^{inter}defined in the independent gradient model based on Hirshfeld (IGMH) has been added as 91th user-defined function, therefore you can easily obtain its value at critical points, plotting it as curve or plane map, etc. Before using it, you should enter option 16 of main function 1000 (a hidden function) to define two fragments. - [2021-Feb-21] Operations on perspective in GUI window become much faster for large systems.
- [2021-Mar-7] Output file of frequency analysis task of CP2K program now can be used as input file for plotting IR spectrum in main function 11.
- [2021-Mar-16] Sphericity index now is automatically printed during quantitative molecular surface analysis. It is a good metric of sphericity of the surface. See end of Section 3.15.1 of manual for detail.
- [2021-Mar-16] .cif file now can be exported by subfunction 2 of main function 100 if cell information has been loaded from input file.
- [2021-Mar-29] IFCT analysis has supported Hirshfeld partition for hole and electron to derive IFCT terms, the procedure is much easier than using the Becke partition in previous version. See updated Section 4.18.8.1.
- [2021-Mar-29] POSCAR file of VASP now can be used as input file.
- [2021-Mar-30] In the option "3 Show atom or fragment contribution to hole and electron and plot the contributions as heat map" of hole-electron analysis, now user can directly choose to use Hirshfeld partition to compute hole and electron composition.
- [2021-Apr-24] For convenience, the 1.2*CM5 charge, which is well-suited for OPLS-AA forcefield, now can be directly obtained by option -16 of main function 7.
- [2021-Apr-29]
**(IMPORTANT)**In suboption 10 of option -1 in topology analysis module, now user is able to ask Multiwfn to only search for CPs between two specific fragments. This is particularly useful for searching intermolecular CPs (the cost may be significantly lower than searching CPs for the whole complex). See part 4 of Section 4.2.6 of manual for practical example. - [2021-Apr-30] When visualizing/exporting electric/magnetic transidion dipole moment density in hole-electron analysis module, now one can choose to export norm of the vector, namely choosing "4: Norm, sqrt(x^2+y^2+z^2)".
- [2021-May-11] Via subfunction 2 of main function 100, now Multiwfn is able to Gaussian input file in internal coordinate (only Cartesian coordinate is supported before).
- [2021-May-28] The CDA module now supports using SCPA method instead of Mulliken method to calculate composition of complex orbitals, just changing the "iCDAcomp" in settings.ini to 2.
- [2021-May-28] Option 37 has been added to main function 6, it can transform restricted wavefunction (R/RO) to equivalent unrestricted wavefunction, in other words, splitting the single set of orbitals of restricted wavefunction to alpha and beta orbitals.
- [2021-Jun-18] CHGCAR, CHG, ELFCAR, and LOCPOT files generated by VASP now can be used as input. They provide atomic information, cell information and grid data for Multiwfn. Evidently, Multiwfn can also be used as a converter to convert them to cube file (using option 0 of main function 13 to export .cub).
- [2021-Jun-19] In the GUI of topology analysis module, a new option has been added to menu: "CP labelling settings" - "Labelling only one CP". After choosing it and input a CP index, e.g. 19, then only label of CP 19 could be shown when "CP labels" check box has been selected. This improvement makes finding a specific CP from topology map much easier for large systems.
- [2021-Jun-23]
**(IMPORTANT)**In topology analysis module, if the function to be analyzed is electron density and bond paths have been generated, after choosing option 0 to view summary of found critical points, now you can directly see the two atoms connecting to each BCP from console window. - [2021-Jun-24]
**(IMPORTANT)**Mixed type of grid (uniform + atomic center grid) now has been supported to calculate basin overlap matrix (BOM) of AIM basins in basin analysis module, the quality of the resulting BOM is significantly better than previous version especially for core orbitals. Specifically, in main function 17, if the real space function used to generate the basins is electron density, after entering option 4 to evaluate LI/DI, or after entering option 5 (or 6) to output BOM (or atomic overlap matrix), Multiwfn will ask you to choose type of integration grid for evaluating BOM. - [2021-Jun-30]
**(IMPORTANT)**A new parameter "ESPrhoiso" has been added to settings.ini. When calculating ESP grid data by Multiwfn's own code, ESP will be evaluated only for the grids around isosurface of electron density of this value for significantly saving computational time. This parameter can also be directly specified via argument, this is why you can find that in the ESPiso.bat and ESPiso.sh scripts in "examples\drawESP\" folder, "-ESPrhoiso 0.001" has been added to the running command. This update makes plotting ESP colored vdW surface map by Multiwfn in combination with VMD (as introduced in Section 4.A.13 of manual) faster than previous version by one order of magnitude! - [2021-Jul-2&10] Spectrum plotting module (main function 11) now is fully compatible with ORCA 5.0. The function for generating ORCA input file (you can enter it by inputting "oi" in main menu) now is compatible with ORCA 5.0; at the meantime, r2SCAN-3c and wB97X-2-D3(BJ) are added as new options.
- [2021-Jul-4] Conceptual density functional theory analysis module (subfunction 16 of main function 100) has been moved to new main function 22 due to its high importance.
- [2021-Jul-5] Option 29 has been added to main function 26, it is used to exchange information between two orbitals, you can use this feature to reorder orbitals.
- [2021-Jul-5] In the function "Visualize (hyper)polarizability via unit sphere and vector representations" (subfunction 3 of main function 300), alpha_vec.tcl and gamma_vec.tcl now can be generated when choosing option 1 and option 3, respectively. If they are run in VMD, anisotropy of polarizability and second hyperpolarizability can be clearly visualized according to length of arrows in X, Y and Z directions. See Section 3.300.3 for detail and updated Section 4.300.3 for example.
- [2021-Jul-7] In the text box at bottom right side of main function 0, or in the interface of orbital composition analysis, or after choosing the real space function "4 Value of orbital wavefunction", now you can input orbital label to choose MO. For example, "h" stands for HOMO, "l+2" stands for LUMO+2, "la" stands of LUMO of alpha, "hb-3" stands for HOMO-3 of beta, etc. This feature is available for R/U/RO(HF/KS) wavefunctions.
- [2021-Jul-14] A new option "5 Use built-in contour values suitable for special purpose" has been added to contour line setting interface in post-process menu of main function 4. Via this option, you can directly adapt built-in contour values recommended for plotting specific functions (orbital wavefunction, density difference, ELF/LOL).
- [2021-Jul-15] In conceptual DFT analysis module (main function 22), after choosing option -1 and then input 2 to change to ORCA, then if you choose option 1 to generate ORCA input files of various electron states, Multiwfn will directly ask you if invoking ORCA to run them to yield .wfn files and meantime automatically delete other files. To make this feature take effect, you should set "orcapath" in setting.ini to actual path of ORCA executable file.
- [2021-Aug-22] The "iloadGaugeom" parameter in settings.ini has been set to 1 by default.
- [2021-Aug-23] ORCA input and output files now can be used as input file to provide atom information for Multiwfn.
- [2021-Aug-23] The equation of ghost-hunter index employed by previous version is found to be erratic (the equation in its original paper is wrong, the virtual MO energy εa should be -εa,) and thus the result is not physically sound, this problem has been fixed in the code. The Section 3.21.7, which describes ghost-hunter index, has been largely rewritten
- [2021-Aug-25] The interface of option 25 of main function 6 (modifying orbital coefficients), has been improved. Now one can choose GTFs or basis functions more easily and flexibly.
- [2021-Sep-3] Via main function 11, UV-Vis and ECD spectra now can be plotted based on EOM-CCSD and (DLPNO-)STEOM-CCSD output file of ORCA.
- [2021-Sep-6] Functionality of subfunction 11 of main function 200 is slightly improved.
- [2021-Sep-8] In fuzzy analysis module and basin analysis module, after choosing corresponding option to ask Multiwfn to output basin/atomic multipole moments, atomic or basin electronic spatial extent <r^2> will be outputted together, which is a useful metric of spatial extent of electron distribution within basins or atoms.
- [2021-Sep-9]
**(IMPORTANT)**Energies of biorthogonalized orbitals and localized orbitals now can be directly evaluated based on the Fock matrix generated by energies and coefficients of MOs, see updated example in Section 4.100.12 and Section 4.19.1, respectively. That means you no longer need to prepare a file containing Fock matrix (such as .47 file) when evaluating the energies of the orbitals, and thus it is much more convenient than before. - [2021-Sep-11] When exporting .47 file using subfunction 2 of main function 100, Fock matrix will also be exported now.
- [2021-Sep-13] The function "Viewing free regions and calculating free volume in a box" (subfunction 1 of mainfunction 300) now fully supports non-orthogonal box/crystal, and two additional switching functions have been supported for smoothing grid data (note that the default one is different to the previous version). Correspondingly, Sections 3.300.1 and 4.300.1 of manual have been updated.
- [2021-Sep-20] In DOS plotting module, the lines representing energy levels now can be shown at bottom of the curves, making the line+curve graph evidently clearer. The examples in Section 4.10 of manual has been updated to exhibit this improvement. In addition, the lines of TDOS corresponding to unoccupied MOs are shown by gray to distinguish them with the occupied MOs.
- [2021-Sep-27] Subfunction 30 has been added to main function 6. This is particularly useful in obtaining EDDB grid data based on EDDB code of D. W. Szczepanik. After loading the .fchk file exported by EDDB code, entering this function, and selecting option 1 (exchange orbital energies in eV with occupation numbers), then occupation numbers will correspond to eigenvalues of Natural Orbital for Bond Delocalization (NOBD). Then if you use main function 5 to calculate grid data of electron density as usual, the resulting grid data will directly correspond to EDDB.
- [2021-Sep-27] VASP POSCAR file now can be created by option 27 of subfunction 2 of main function 100.
- [2021-Sep-27] Functions related to (hyper)polarizability analysis have been collectively moved to a new main function 24.
- [2021-Oct-10] When loading .gro/pdb/pqr file, residue names and indices will also be loaded, and when saving present system to .pdb/pqr file, these information will be kept.
- [2021-Oct-10] More options have been added to GUI of main function 5, in which you can save current plotting settings to isosur.ini and load the settings from it next time.
- [2021-Oct-18] In main function 0, a new option "Toggle showing all boundary atoms" has been added to "Other settings" in menu bar. If a file containing cell information is used as input file, this option is able to show all atoms at boundary of the cell, so that crystal structure can be visualized more clearly.
- [2021-Oct-20] Main function 25 is added, it is a collection of all methods for measuring electron delocalization and aromaticity supported by Multiwfn.
- [2021-Oct-22 & 2021-Nov-17] The option -5, which is used to export basins generated by basin analysis module, has been significantly extended. Via this option, now it is able to easily plot nice ELF isosurface map colored by basin types (monosynaptic, disynaptic and others) via VMD software. In addition, this option now allows to export grid data of function value in the region of specific basins as cube file, so that you can then visualize isosurface via e.g. VMD only for the selected basins. See the newly added example in Section 4.17.10 of manual.
- [2021-Nov-3] Analytic gradient for Shannon entropy density, Fisher information density and second Fisher information density (user-defined functions 50, 51, 52, respectively), as well as analytic Hessian for Shannon entropy density and Fisher information density, have been implemented. So their topology analysis becomes more accurate and efficient than before (older version only supports topology analysis based on numerical gradient and Hessian for them).
- [2021-Nov-8] When outputting atom δg indices and atom pair δg indices to atmdg.txt in IGM or IGMH analysis module, percentage contributions are also outputted together, this is useful to examine relative importance of various atoms and atom pairs for the studied interfragment interaction.
- [2021-Nov-8]
**(IMPORTANT)**The formula used in IGM and IGMH analyses has been improved to make the result more reasonable (the definition of the IGM type of gradient norm has slightly changed), all data related to IGM and IGMH analyses are affected and somewhat different to previous version. In previous version the δg distribution somewhat violates structure symmetry, this problem is resolved by this update. This update also makes isosurfaces in IGMH map notably smoother. - [2021-Nov-21] After performing IGM or IGMH analysis, integrals of δg, δg
^{inter}and δg^{intra}over the whole space are outputted on screen. The integral of δg^{inter}is particularly useful in quantitatively analyzing interfragment interaction strength. - [2021-Dec-4] In the atmdg.pdb file exported by option 6 in the post-process menu of IGM and IGMH analysis modules, the "Occupancy" field now records percentage atom δg indices, which exhibits percentage controbution of various atoms to interfragment interaction. In VMD, you can color atoms according to this property to vividly exhibit importance of each atom, see updated IGM example in Section 4.20.10 of Multiwfn manual.
- [2021-Dec-7] Calculation of PEOE and EEM charges has supported considering periodic boundary condition.
- [2021-Dec-15] To screen uninterested IRI isosurfaces in extremely low electron density regions, "IRI_rhocut" parameter is added to settings.ini and has default value of 5E-5 a.u. IRI is set to an arbitrarily large value (5) in the regions where electron density is equal or smaller than this parameter so that IRI isosurfaces will not appear at commonly adopted isovalue. This treatment is automatically disabled during topology and basin analyses to avoid causing artificial extrema.
- [2021-Dec-20] In the interface of plotting transition density matrix, new options 10 and 11 are available for changing label size and number of decimal places of Z-axis labels; in addition, option 7 has been extended, now it can also set stepsize between labels of Z-axis.
- [2021-Dec-27] Multiple frame .mwfn file has been supported.
- [2022-Jan-2] .sdf molecular structure file format has been supported.
- [2022-Jan-16] When setting frequency scale factor (via option 14 in main function 11), now user can input lower and upper limits of frequencies, only the frequencies within the range will be scaled by the inputted scale factor.
- [2022-Feb-7] A new option "Perform integration for subregion of some domains according to range of sign(lambda)*rho" has been added to post-processing menu of domain analysis module (subfunction 14 of main function 200), see updated Section 3.200.14 of manual for detail. It may be useful in studying interactions by integrating specific real space function in the regions of interest.
- [2022-Feb-11] The quality of fingerprint plot has been significantly improved! See updated Section 4.12.6 of Multiwfn manual.
- [2022-Feb-17] "Toggle between perspective and orthographic views" option has been added to "Set perspective" drop-down list in menu of GUI of showing 3D objects.
- [2022-Feb-25] At the end of the .wfn file exported by Multiwfn, $MOSPIN field is outputted to explicitly indicate spins of recorded orbitals. This design is the same as Molden2aim code.
- [2022-Feb-25] Calculation speed of real space functions is markedly improved if general contracted basis set is used (e.g. ANO series, MOLOPT series of CP2K).
- [2022-Mar-1] Calculation cost of option "Calculate hole-electron Coulomb attractive energy" in post-process menu of hole-electron analysis has been largely reduced.
- [2022-Mar-15]
**(IMPORTANT)**After performing interfragment charge transfer (IFCT) analysis, CT(%) and LE(%) are directly shown on screen, this is quite convenient for determining type of electron excitation. - [2022-Mar-22] Improvements of domain analysis module: (1) Option 12 is added to post-processing menu, it can export X,Y,Z and grid data value of all grids in a selected domain to a plain text file. (2) When use option 1 or 2 to integrate domain(s), now one can select to directly use the grid data recorded in memory as the integrand. (3) Periodicity can be taken into account (determined by option "4 Toggle considering periodicity during domain analysis" in domain analysis interface). (4) Option 4 is added to post-processing menu, which can sort domain indices according to volume of domains, so that important domains (often largest ones) can be more easily studied.
- [2022-Mar-28] More options are added to "Set camera" droplist in menu bar of 3D GUI to flexibly control viewpoint, such as rotation angle along screen.
- [2022-Apr-8] Color of interbasin surfaces generated by topology analysis module now can be set by "interbasin_RGB" in settings.ini.
- [2022-Apr-20] User-defined functions 1101 and 1102 have been added, they correspond to DFT exchange-correlation potential of alpha and beta spins for open-shell system, respectively (exchange-correlation potential in older version only supports closed-shell case via user-defined function 1100).
- [2022-Apr-21] Spin-flip TDDFT of ORCA is supported by electron excitation analyses (main function 18). Currently only a few functions, including generating natural orbitals of excited state, hole-electron analysis and related analyses, are formally supported, other functions were not tested. See introduction of input file in Section 3.21.A of manual for details.
- [2022-May-16] Source code of Multiwfn have been compatible with gfortran and can link other blas/lapack libraries instead of MKL.
- [2022-May-18] For plotting IR spectrum generated by xtb program, now users should use the "vibspectrum" file outputted by "--ohess" task as input file of Multiwfn. xtb older than 6.5 is no longer formally supported.
- [2022-May-24] Better compatible with wavefunctions in which some ghost atoms do not have any basis function.
- [2022-Jun-13] Cost of generating density matrix for multiconfigurational wavefunction of large systems is significantly reduced.
- [2022-Jun-19]
**(IMPORTANT)**Searching critical points of electrostatic potential by topology analysis module (main function 2) becomes significantly faster and more robust, relevant examples have been added as Section 4.2.9 in manual. - [2022-Jun-19]
- [2022-Jun-22] Analytic gradient and Hessian of norm of electron density gradient, reduced density gradient (RDG), interaction region indicator (IRI), and information entropy density are available in Multiwfn now. Therefore, their topology analysis becomes faster and more accurate than before.
- [2022-Jul-4] Minima of van der Waals potential now can be accurately located by topology analysis module, see Section 4.2.10 of manual for example.
- [2022-Jul-15] Some improvements on fuzzy analysis module: (1) For integrating a real space function via option 1, atomic grid has been replaced with molecular grid, this improves integration accuracy significantly for some functions (e.g. Laplacian of electron density) when Hirshfeld or Hirshfeld-I partition is used. (2) Option -6 is added to the interface, which enables using considerably more accurate but more expensive molecular grid instead of the default atomic grid for evaluating atomic overlap matrix (AOM) (3) Accuracy of AOM is notably enhanced when diffuse functions are heavily employed when Hirshfeld(/-I) partition is used. (4) When "ispecial" in settings.ini is set to 3, then all MOs will be taken into account in AOM calculation even if current wavefunction is single-determinant.
- [2022-Jul-16] IRIscatter.gnu has been provided in "examples\scripts" folder, by which you can plot colored scatter map between IRI and sign(λ2)ρ via gnuplot. See Section 4.20.4 of manual for example of use.
- [2022-Jul-28] Windows version of Multiwfn now can invoke significantly larger memory than before, thus avoiding crash when deal with huge system.
- [2022-Oct-15] MOPAC input file (.mop) now can be used as input file for providing atom information.
- [2022-Nov-27] Option -1 has been added to subfunction 5 of main function 18. By this option, you can request Multiwfn to skip calculation of transition dipole moments between excited states while only calculate them between ground state and excited states, and hence saving quite a lot of time when the system is large.
- [2022-Dec-1] Spectrum plotting module (main function 11) now is able to plot NMR and UV-Vis spectra based on output file of BDF program. Electron excitation analysis module (main function 18) now supports BDF output file. Thanks Cong Wang for contributing relevant code.
- [2022-Dec-18] Parallel efficiency for calculating grid data has been significantly improved on computer with dozens of CPU cores. Thanks to Igor S. Gerasimov for providing hint.

- [2020-Nov-30] Section 4.17.9 has been added to manual to illustrate how to correctly calculate atomic energy (contribution of atomic basin to total electronic energy).
- [2021-May-20] Example of plotting fluorescene spectrum using main function 11 is given in Section 4.11.11. The process of plotting phosphorus spectrum is also mentioned.
- [2021-May-28] A new Section 4.16.4 is added. This section illustrates how to correctly perform CDA analysis based on ROKS wavefunction for open-shell system to avoid explicitly distinguish alpha and beta spins during discussing CDA result and analyzing orbital interaction diagram.
- [2021-Jul-14] A new Section 4.4.11 is added to illustrate how to plot a very clear and pretty color-filled contour line map for exhibiting 4pz atomic orbital of Kr atom.
- [2021-Aug-9] A new Section 4.2.8 is added to illustrate how to perform topology analysis for density difference. The deformation density of H2O is taken as the example.

- [2020-Aug-20] When invoking Multiwfn via command line, the value after -nt or -uf argument cannot be properly parsed if the value is not a single digit.
- [2020-Sep-4] In the spectrum plotting function (main function 11), the option used to modify oscillator strength does not work if there is only one system.
- [2020-Sep-12] In the AdNDP module, the program crashes when entering the GUI interface for the second time to visualize AdNDP orbitals
- [2020-Sep-22] For unrestricted wavefunctions, subfunction 34 of main function 6 is unable to correctly set occupation of inner-core MOs.
- [2020-Oct-14] The "Centroid distance between the two orbitals" reported by subfunction 11 of main function 100 used incorrect unit (Bohr rather than Angstrom as it should be).
- [2020-Oct-23] The "Select fragment" function in main function 0 do not always work normally when .mol and .mol2 are used as input files.
- [2020-Oct-24] Many subfunctions in electron excitation analysis module does not properly work for output file of electron excitation calculation with specific state solvation model in Gaussian.
- [2020-Oct-28] In topology analysis module, correspondence between atom and nuclear critical point cannot be correctly identified for some highly polar hydrogens. This issue sometimes severely affects option 8 of option -5 in this module.
- [2020-Dec-9] The NBO plot file generated by ORCA in combination with NBO cannot be properly loaded.
- [2020-Dec-16] Fixed a bug of loading NBO output information in AdNDP module when number of atoms exceeds 99.
- [2021-Feb-2] The option "4 Set the range of axes" in "Fingerprint map analysis" interface of main function 12 does not work properly.
- [2021-Feb-25] PDOS map based on Hirshfeld or Becke partition cannot be normally plotted if there is no fragment containing more than one atom.
- [2021-Mar-16] Fixed a bug of calculating size of planar system ("size" command in subfunction 21 of main function 100)
- [2021-May-26] Fixed a bug: mwfn file containing g functions cannot be properly treated in some analyses.
- [2021-Jun-2] Fixed a problem: In the output.txt exported by aNCI function, the column of the 4th and 5th columns should be altered, so that it can be normally plotted by RDGscatter.gnu via gnuplot
- [2021-Jul-2] In the spectrum_curve.txt exported by main function 11, the outputting format is inappropriate when the value is extremely small.
- [2021-Sep-1] .mwfn file cannot be successfully loaded when linearly dependent basis functions are presented (in this case the number of orbitals is smaller than number of basis functions)
- [2021-Sep-1]
**(IMPORTANT)**The result of AIM basin integration in basin analysis module is slightly inaccurate, this bug was introduced since Multiwfn 3.5. - [2021-Sep-30] When there are very large coefficients in NBO plot file, sometimes no space occurs between two neighbouring values and the file cannot be loaded.
- [2021-Oct-22] When using NMR spectrum plotting function (main function 11), if the input file is output file of Gaussian or ORCA NMR task at MP2/double-hybrid functional level, the SCF shielding tensor is loaded, this is inappropriate; in the new version, MP2/double-hybrid functional shielding value is loaded instead in this case.
- [2021-Nov-1] When plotting NMR spectrum via main function 11 for output file of ORCA, if limitation of elements is set in ORCA input file (e.g. calculating chemical shifts only for hydrogens), Multiwfn will crash when loading data. This incompatibility has been resolved.
- [2021-Nov-2] Multiwfn crashes after selecting a symmetrization method in subfunction 9 (generate and export transition density matrix) of main function 18.
- [2021-Nov-4] After printing/exporting overlap matrix by subfunction 7 of main function 6, the diagonalized overlap matrix is not restored, making some of subsequent analyses wrong.
- [2022-Jan-5] The option "1 Calculate the first and second moments of the function" in subfunction 11 of main function 200 does not work normally under Linux possibly due to bug of Intel Fortran compiler. This problem has been overcome.
- [2022-Feb-11] An issue of calculating local contacting surface area in Hirshfeld surface analysis is fixed. In old versions, the sum of areas of all kinds of local contact surface is (unexpectedly) not equal to the total Hirshfeld surface area.
- [2022-Mar-11] Stepsize of generating topology path cannot be changed via corresponding option in "-2 Set path generating parameters" in topology analysis module.
- [2022-Mar-22] Domain analysis does not work normally if number of grids in a domain is larger than 1000000.
- [2022-Apr-11] NMR plotting function is incompatible with ORCA output file when "NUCLEI" in %EPRNMR is used to request to only print shielding for specific atoms.
- [2022-Jun-13] Printed wall clock time cost is incorrect or even negative if the calculation span the zero hour of the day.
- [2022-Jun-13]
**(IMPORTANT)**Natural orbitals of excited state generated by subfunction 13 of main function 18 is not fully correct, because the cross term involved in the calculation of density matrix of excited state was missed. - [2022-Aug-12] Subfunction 2 of main function 100 now can export GROMACS .gro file if present system is periodic.

- 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 C
_{60}, 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.

- 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.

- [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.
- [2022-Oct-10] Section 4.12.4 has been largely extended, now it also describes how to plot Fukui function mapped molecular surface with surface minima and maxima.

- 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.

- 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.)

- 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.

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.

- 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.

- 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.