Multiwfn forum

cfspence

Member

Registered: 2019-04-20

Posts: 3

Omitting atoms in RESP calculation?

I'm attempting to follow the ONIOM QM/MM preparation tutorial found in Chapter 9 of the _Exploring Chemistry with Electronic Structure Methods_, 3rd Edition from Gaussian (https://gaussian.com/expchem3/). That tutorial works with a modified variant of the green fluorescent protein, GFP, (1w7s.pdb). The tutorial uses R.E.D. III tools to compute the RESP charges on the chromophore portion (that software appears to no longer be available for download). There are unfilled valances where the chromophore attaches to the protein. Methyl groups replace these unfilled valances prior to RESP calculation. The tutorial says to tell the RED software not to calculate RESP charges for these methyl groups. Is it possible (or even necessary) to do that when calculating RESP charges on the chromophore with Multiwfn?

Thanks, in advance, for any advice.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: Omitting atoms in RESP calculation?

When using Multiwfn to calculate RESP charges for this system, you can manually write a charge constraint file, in which you define that all atoms in the methyl groups have zero charge. You will immediately understand how to do this after reading the RESP examples in Section 4.7.7 of Multiwfn manual.