Multiwfn forum

axeljr7

Member

Registered: 2023-07-31

Posts: 11

initial guess for population analysis

Dear all,
is it possible that in calculating partial charges, we can provide some user-defined initial guesses for partial charges?
That would be so useful and helpful.
Kind regards

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: initial guess for population analysis

Hello,

There is no so-called initial guess for calculating partial charges. Partial charges only depend on the wavefunction loaded into Multiwfn.

axeljr7

Member

Registered: 2023-07-31

Posts: 11

Re: initial guess for population analysis

Hello,

There is no so-called initial guess for calculating partial charges. Partial charges only depend on the wavefunction loaded into Multiwfn.

Assume we want to fit partial charges in a way to get the best fit to ESP (as usual e.g. in ChelpG and MK methods). There should be some initial guesses to be improved in each iteration of fitting or I am missing something?
Similarly, for Hirshfeld partitioning approaches that work iteratively, (e.g. Hirhfeld-I), if we start from a good guess of initial partial charges, I suppose we can reduce the number of iterations. Is that correct?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: initial guess for population analysis

CHELPG and MK do not involve iteration process. They are obtained simply by solving a set of linear equations

Result of Hirshfeld-I charges is independent of initial guess. Although a good guess may lead to faster convergence, it is not easy to determine an evidently better guess than Hirshfeld charge.