Multiwfn forum

MLM211

Member

Registered: 2025-02-03

Posts: 1

ESP at nuclear position vs ESP at CP of nucleus

Hi,

I have been using Multiwfn to try and do topology analysis. I've noticed a discrepancy in values, and was wondering which value is appropriate. I followed the procedure in 4.1.2 in the manual emulating getting dVnuc like Suresh's work.
If I submit a1, I get:
Total ESP:  0.9771869440E+03 a.u. ( 0.2659061E+05 eV, 0.6131946E+06 kcal/mol)
Total ESP without contribution from nuclear charge of atom     1:
-0.5916237480E+01 a.u. ( -0.1609890E+03 eV, -0.3712498E+04 kcal/mol)

Now, if I use the same input file and submit:
2
2
3
0

get CPs and coordinates I get this line for atom1:
7    0.33664193   -0.14486139    1.08024924   (3,-3)   Nucleus:    1(La) (in Bohr)

If I go back to 1 Output all properties at a point
and submit
0.33664193   -0.14486139    1.08024924
and select that these coordinates are in bohr I get:
Total ESP:  0.3456113230E+10 a.u. ( 0.9404562E+11 eV, 0.2168746E+13 kcal/mol)

Can you explain which value is more applicable to MESP topology analysis and using dV values like Suresh's work?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,955

Website

Re: ESP at nuclear position vs ESP at CP of nucleus

First, note that nuclear CP position is not exactly identical to nuclear position (although for non-hydrogen atoms, the difference is almost negligible).

Second, note that ESP defined in common way at a nuclear position is meaningless, because it must be infinitely large due to the contribution to ESP from the nucleus at the corresponding position. What is meaningful at a nuclear position is the ESP without contribution of the corresponding nucleus, that is "Total ESP without contribution from nuclear charge of atom xxx" in the output of main function 1 of Multiwfn. The ESP value at nuclear position involved in Suresh's work corresponds to this quantity.