Multiwfn forum

saeed_E

Member

Registered: 2019-12-21

Posts: 237

A question regarding QTAIM calculation in solution phase

Dear Tian,
I hope you are doing well, my nice friend.
If possible and, as always, you kindly let me, I am going to ask you two questions:

1- Please suppose we are studying an intermolecular interaction in the presence of a given solvent to further perform QTAIM analysis finding corresponding descriptors in a specific BCP. I think, one should initially optimize the dimer structure in the presence of given solvent (using SCRF keyword) and, then, perform a single-point energy calculation in vacuum to obtain corresponding chk/fchk file for QTAIM analysis. In other words, we just need geometry in the presence of solvent and, QTAIM does not need solvent to be included in the Hamiltonian (wavefunction). Do you agree with me?

2- Using "iuserfunction" I want Multiwfn prints out the value of delta_g_inter in a specific BCP. Could you please let me know how this goal can be reached?

Sincerely yours,
Saeed

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,770

Website

Re: A question regarding QTAIM calculation in solution phase

Dear Saeed,

1 Solvent environment polarizes electron density notably, if you hope to study electronic structure in solvent environment, then the wavefunction must also be generated with solvation model.

2 delta-g_inter is user-defined function 91, please check Section 2.7 of Multiwfn manual for details. To realize your goal, you should:
(1) Set iuserfunc in settings.ini to 91
(2) Boot up Multiwfn and load wavefunction file
(3) Using option 16 in main function 1000 to define fragments
(4) Enter topology analysis module to search BCP, then use option 7 to check properties of the BCP of interest, read user-defined function value.

Best,

Tian

saeed_E

Member

Registered: 2019-12-21

Posts: 237

Re: A question regarding QTAIM calculation in solution phase

Dear Tian,
Many many thanks for your highest kindness to prompt reply guiding me with highly informative and valuable points.
Consequently, in addition to QTAIM analysis, any other analysis such as IGMH and so on in the presence of a solvent MUST include solvent effects in the generated wfn/fch/fch files; that is, this files must be generated under SCRF implementation. Is it quite true?

Sincerely yours,
Saeed

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,770

Website

Re: A question regarding QTAIM calculation in solution phase

It is true

saeed_E

Member

Registered: 2019-12-21

Posts: 237

Re: A question regarding QTAIM calculation in solution phase

Dear Tian,
Thank you very very much.

Sincerely,
Saeed