Multiwfn forum

Ainosya

Member

Registered: 2024-12-06

Posts: 1

Discrepancy in Electronic Spatial Extent Between Multiwfn and Gaussian

Hello,

I am trying to obtain the electronic spatial extent using different software. To do so, I modified the settings.ini file in Multiwfn by setting iuserfunc = 3.

Multiwfn returns a value of 21092.4988259881, whereas my g16.log output gives 18436.6750. Is there a specific reason that could explain such a discrepancy?

I am unable to upload my files to the forum due to their large size, but could you please confirm whether my procedure for obtaining ⟨R²⟩ using Multiwfn is correct, or if I might be doing something wrong?

Thank you

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,978

Website

Re: Discrepancy in Electronic Spatial Extent Between Multiwfn and Gaussian

I think you ran Multiwfn in a wrong way. Taking H2O as an example:

%chk=C:\gtest\H2O.chk
#p hf/6-31G*

test

0 1
      O       -0.00000000   -0.00000000    0.11930800
      H        0.00000000    0.75895300   -0.47723200
      H       -0.00000000   -0.75895300   -0.47723200

The <r^2> outputted by Gaussian is
Electronic spatial extent (au):  <R**2>=             19.0512

If you set iuserfunc to 3, and boot up Multiwfn and load the .fch file produced by the above task, then run
100
4
100

You will obtain
Final result:       19.051245015
which is exactly the same as that outputted by Gaussian