Multiwfn forum

akku

Member

Registered: 2021-12-08

Posts: 6

How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

First of all, thank you very much for such an amazing software. It works so efficiently and smoothly.
I have an inquiry about obtained electrostatic potential (ESP) result in Multiwfn, which I generated using a .wfn file. I wanted ESP as a function of r alone (in the form of 1D). Hence, I choose ' 3 Output and plot specific property in a line' option after that I opted for '12 total ESP'. After opting option 12 for total ESP, I further selected option '2 Input coordinate of two points to define a line'. The result comes as ESP Vs position. I understand position refers to 'r' here. I would like to ask if calculated ESP is averaged over all the theta (polar angle) and phi (azimuthal angle) directions to give a 1D result; in general, if the ESP result is obtained using some scaling factor apart from the formula given in the Multiwfn manual for total ESP (Page no. 24). Kindly reply to me in this regard.

Thank you very much in advance.

Last edited by akku (2021-12-08 15:13:10)

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

The curve of a real space function plotted by main function 3 is not spherically averaged over theta and phi.

If you need spherically averaged curve, you can enter main function 200 and choose subfunction 5. After calculating, in the post-processing menu select option "7 Export the spherically averaged function". See Section 3.200.5 of Multiwfn manual for detalis.

akku

Member

Registered: 2021-12-08

Posts: 6

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

Thank you very much for your very quick response. Your suggestions helped me to find what I intended to calculate.

Thanks a lot!!!

akku

Member

Registered: 2021-12-08

Posts: 6

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

I have a small query regarding the radial distribution function for electron density using Multiwfn. I wanted to calculate radial electron density or simply electron density using a .wfn file. I successfully obtained result too using main function 200 and sub-function 5. A bit of confusion arises here when I try to compare RDF or spherically averaged RDF with some reported radial electron density; difference within a multiplicative factor arises. I would like to ask you if the RDF is exactly same as radial electron density. In the same context, I would like to know if spherically averaged RDF exactly represents electron density of a system. I have already visited the Multiwfn manual in this regard. Please give me your clarifications. It would greatly help me to clarify my doubts.
Thank you very much in advance.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

"radial electron density" is not a well-defined word, it may refer to RDF of electron density, or refer to spherically averaged radial electron density (f_sph), their relationship can be found in Section 3.200.5 of Multiwfn manual.

Also pay attention to the unit used by Multiwfn, if unit is not explicitly shown on screen or output, the unit is a.u.

akku

Member

Registered: 2021-12-08

Posts: 6

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

Thank you very much for your quick reply. I was just trying to get an idea of the relation; but I could not find out. Please suggest me some way to calculate electron density from a .wfn file, if possible. I precisely mean an electron density, which is a function of r; similar to what we usually calculate for atomic electron density.

Thank you very much in advance.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

Thank you very much for your quick reply. I was just trying to get an idea of the relation; but I could not find out. Please suggest me some way to calculate electron density from a .wfn file, if possible. I precisely mean an electron density, which is a function of r; similar to what we usually calculate for atomic electron density.

Thank you very much in advance.

If you just need to calculate electron density at a pointr, you can enter main function 3 and input the coordinate, various properties including electron density will be outputted.

akku

Member

Registered: 2021-12-08

Posts: 6

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

Thank you so much for your quick response. I am aware of function of the main function 3. All the uncertainty arose due to comparison of my results with a reported work, where radial electron density Vs radial distance plot is given (without providing any expression for their radial electron density). The comparison shows up a difference upto some scaling factor, however the qualitative features match very well.

Thanks a lot once again.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,777

Website

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

If your result only differ with data in literature by a scale factor, please pay attention to the unit. The unit has already been explicitly given by Multiwfn, if you have doubt on the unit of published data, please contact correspondence author.

akku

Member

Registered: 2021-12-08

Posts: 6

Re: How to interpret ESP obtained by Multiwfn using a .wfn file

Dear Prof. Tian Lu,

Thank you very much for your suggestion. I had taken care of the unit used in their work; it is all a. u. as mentioned in their plots. As for as Multiwfn is concerned, I understand the function value is by default given in a. u. and the observable along the X-axis is either a. u. or angstrom (as shown on screen while exporting the files).
I compared another result from the same work and found an excellent agreement both quantitatively and qualitatively. It seems then that the result which I was trying to get a similarity with may have some intrinsic differences originating from its molecular structure etc. Such reasons may cause a difference in radial electron density of the molecule.

Thanks a lot once again for your valuable time.