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sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

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Calculate the RESP and AM1-BCC charges of a molecule

Today I notice there is a post on PSI4 forumhttp://forum.psicode.org/t/calculate-th … ecule/1276

I calculated Mulliken atomic charges of an organic small molecule using Psi4. I also need to calculate both the RESP and AM1-BCC charges for the same molecule. Do you know that how I can calculate the RESP and AM1-BCC charges of a molecule with Psi4?

I copy my reply here since the content may be useful for others

You can use my code Multiwfn (//www.umsyar.com/multiwfn) to calculate RESP charge, the details of RESP is documented in Section 3.9.16 of Multiwfn manual, related examples are given in Section 4.7.7, you will find using Multiwfn to derive RESP charges is extremely easy. The .fch file generated by PSI4 can be directly use as input file, the way of generating .fch file via PSI4 is explicitly mentioned at begnning of Chapter 4 of Multiwfn manual.

Commonly, RESP works much better than AM1-BCC, the main purpose of the latter is to obtain charges with similar feature and quality as RESP but with evidently lower cost. Since evaluation of RESP charges for small molecule is never expensive, I don't think there is any reason to use AM1-BCC.