For example, you want to calculate cube file of MO(26)^2-MO(25)^2, boot up Multiwfn and input below commands

test.molden

200

3 // Export cube file containing orbital wavefunction

25,26 // The two orbitals needed later

2 // Medium quality grid

1 // Export grid data

Now you have orb000025.cub and orb000026.cub in current folder.Reboot Multiwfn and input

orb000026.cub

13 // Process Grid data

11 // Grid data calculation

11 // A^2-B^2=C operation

orb000025.cub

Now, the grid data in memory corresponds to MO(26)^2-MO(25)^2, you can then use option -2 to visualize it, or use option 0 to export it as .cub file.

Any kind of valence electron density analysis can be easily done via Multiwfn, including plotting it as map, topology analysis, basin analysis and so on. The way of plotting valence electron density map is mentioned in Section 4.6.2 of Multiwfn manual.

Hoping that valence electron density analysis will be become a popular tool for studying electronic structure problems!

]]>Dear Dr. Lu

What does it mean to excitation binding energy?

wawa

It should be exciton binding energy

]]>Indeed there is no much difference between density and electrons per grid point for uniform cubic and rectangular grids.

I was a bit confused, because for more "complicated" radial+angular grid the weight for each point is not just dx*dy*dz.

One gets large density contribution close to nuclei, which vanishes once it is multiplied by weights.

https://www.researchgate.net/post/Is_th … l_analysis

Title:Is there anything interesting in the UV-Vis spectrum (excluding energy transition, Wavelength max, homo-lumo) for molecular structural analysis?

I like to include anything novel approach in the my research write up. I wanna try anything different approach from prototypical old approach. Please give me some suggestions.

My reply

If you meant you want to add some advanced or novel analyses for studying electronic excitation problem, there are some methods you may consider, all of them can be easily realized via Multiwfn in combination with a popular quantum chemistry code such as Gaussian and ORCA. Multiwfn is freely available at http://sobereva.com/multiwfn

(1) Density difference map between excited state and ground state: This analysis helps you to understand electronic structure reorganization during electronic transition. This can be easily done using Multiwfn, see Section 4.5.5 of Multiwfn manual for example

(2) Transition density matrix map: This enable you to immediately capture the main molecular region involved in the transition and investigate coupling between various atoms. See Section 4.18.2 of Multiwfn manual for example.

(3) Interfragment charge transfer analysis: This analysis describes amount of electron transferation between two arbitrarily defined molecular fragments. See Section 4.18.6 of Multiwfn manual for example.

(4) Analysis of transition dipole moment contributed by various molecular fragments: Oscillator strength is positively proportional to transition dipole moment, which is possible to be decomposed to molecular fragment contributions. Clearly this analysis helps you understanding how various fragments affect strength of spectrum peak. See Section 4.18.5 of Multiwfn manual for example.

(5) hole-electron analysis: This is a powerful module of Multiwfn program, it can calculate hole and electron distribution (electronic excitation can be represented as hole->electron transition), and based on them, charge transfer distance (i.e. distance between centroid of hole and electron) and overlap between hole and electron can be calculated, and then used to identify type of electronic excitation. Atomic contribution to hole and electron can also be quantified. Besides, Coulomb attractive energy between hole and electron can be evaluated. Furthermore, this module can draw transition dipole moment map, so that contribution to transition dipole moment from every position in 3D space can be vividly examined.

(6) Natural transition orbitals (NTO) analysis: This is a very popular analysis method, it is quite useful when you need to study orbital transition but there is no unique dominating molecular orbital pair. See Section 4.18.4 of Multiwfn manual for example.

(7) Population analysis: By comparing electronic population on atoms or atomic orbitals between ground and excited states, you can make clear how charge transfer occur at the atomic or atomic orbital scale. Example of population analysis can be found in Section 4.7 of Muliwfn manual.

(8) Plotting contribution to spectrum of individual transitions. The spectrum plotting module of Multiwfn enables the overall spectrum be decomposed to individual contribution from various electronic transition, so that the underlying character of overall spectrum can be more clearly understood. See Section 4.11.2 of Multiwfn manual for example.There are also many other functions in Multiwfn that closely related to electronic excitation problem, such as TrEsp(transition charge from electrostatic potential), ghost-hunter index, delta-r index, orbital overlap analysis. Theoretical introductions as well as examples can be found in the manual.

thank you for your fast reply! Loosening the convergence criteria did the trick. I tried to tighten the convergence criteria - that was the wrong way to go obviously. It finally worked with gradient norm convergence set to 1.0e-04 and displacement convergence at 1.0e-05.

Best wishes,

Michael

is it possible to compute critical points and bond paths only for selected pairs of atoms? Out of more than 400 BCps only 5 are of interest for me, and looking for those every time for multiple structures is a pain.

A:

You can select "1 Search CPs from a given starting point", then input index of two atoms, then midpoint of these two atoms will be used as starting point for searching CPs. I think this mode should be appropriate for your case.

Nice work! Were all pictures generated using Multiwfn?

Yes, all of them were done by Multiwfn, based on wavefunction information outputted by Gaussian.

]]>Thanks a lot for a prompt reply, you are right---the segfault was because I forgot to increase the stack size, it works great now!

Cheers,

-Qadir

:-( Almost all netdisks outside China region was blocked by goverment, including megz (AFAIK, only filedropper, Sendit and sendspace are accessible).]]>

In this forum in fact you can upload attachement, please check http://sobereva.com/wfnbbs/viewtopic.php?id=3

Please upload file, so that I can better check the reason. If you are really unable to upload file, please send the file to my mailbox: sobereva[at]sina.com.

Multiwfn is able to normally recognize Cl.