Multiwfn forum / A strange result in Atomic dipole moment corrected Hirshfeld charges

Re: A strange result in Atomic dipole moment corrected Hirshfeld charges

dummy@example.com (sobereva) — Fri, 30 Sep 2022 20:54:47 +0000

This problem is irrelevant to basis set, but mostly related to spatial arrangement of atoms in special configuration.

Re: A strange result in Atomic dipole moment corrected Hirshfeld charges

dummy@example.com (PedroSilva) — Fri, 30 Sep 2022 19:25:20 +0000

Yes, I have meanwhile computed CM5 charges, and they look completely reasonable.

PS: in case this might be important for the diagnosis of the origin of the error, my computations had an ECP on Cu (SBKJC) and 6-311G(2d,p) on the other atoms

Re: A strange result in Atomic dipole moment corrected Hirshfeld charges

dummy@example.com (sobereva) — Fri, 30 Sep 2022 18:44:59 +0000

Please try to use Multiwfn to calculate Hirshfeld-I or CM5 charges, they are usually comparably reasonable as ADCH. In very rare cases, I noticed that the current algorithm for calculating correction charges of ADCH is not quite numerically stable. If Hirshfeld-I or CM5 works in the present case, you can use them instead.

A strange result in Atomic dipole moment corrected Hirshfeld charges

dummy@example.com (PedroSilva) — Fri, 30 Sep 2022 11:17:37 +0000

I have been analyzing some results on systems composed of two fragments:
1) an alkyne of the form CH3-C(triple-bond)C-X (where X is NH2, CH3, CH3, OCH3 or SCH3)
2) [Cu(CH3)2] -

The ADCH charges computed for the pi-complexes and reaction intermediates look very reasonable, but for the pre-reactional complexes (composed of the two intact fragments at around 3.2 to 4 angstrom of each other) I get very large charges on the Cu (from -3.5 to +9.5) and very large charges on the methyl carbons attached to the Cu (the total charge of the Cu(CH3)2- moiety does remain reasonable, at -0.9) . The charges on the alkyne moiety look reasonable. At first I assumed this strange behavior might be due to the large electric dipole of the [Cu(CH3)2]- moiety , but I now know it must be something else because this strange behavior does not happen when X is NH2 or PH2, only when X=CH3, OCH3, or SCH3 , or when I compute the isolated [Cu(CH3)2] - even though the [Cu(CH3)2]- moiety where the "error" (?) appears has the same geometry in all cases.

This unfortunately makes me a little wary of using this method for my other comparisons.

Has anyone here found such behavior in other systems?