From: Daniel Fellner (
Date: Thu Jun 18 2020 - 23:17:42 CDT

Hi all,

In the CGenFF papers, it mentions that compounds with sulfur were run at
MP2/6-31G(d) level of theory. I've been having trouble getting the
objective function to fit using the HF/6-31G(d) water data, so I thought I
would try it with MP2.

I was wondering, do the water shift (-0.2) and scale (1.16) settings need
to be changed? And should I just give FFTK the location of the MP2 file
where it asks for HF? And use an MP2 calculation of the water-sp?

Also, I've seen it mentioned in the CHARMM forums that the distances aren't
actually considered in the original CGenFF procedure, and I certainly get
much better convergence if I turn the distance weight down. I wonder how
this would relate to sulfur-containing compounds?

*Daniel Fellner BSc(Hons)*
PhD Candidate
School of Chemical Sciences
University of Auckland
Ph +64211605326