[gmx-users] histidine charges in ffopls.rtp

[Mark Abraham]

Marius Retegan wrote:
> Hello
> I would like to know what charges are in the ffopls.rtp in the case of HISA.
> In the data below, on the 3rd column are the charges from Gromacs and
> on the 4th column are the charges for the same residue from a personal
> communication of opls parameters from prof. Jorgensen.

The primary source for "OPLS/AA" is the paper in which they and the 
method by which they were developed was published. GROMACS (should) have 
duplicated that information :-) They may well have been revised since 
then in some cases, and either there's subsequent literature, or there 
needs to be some accompanying discussion in this "personal 
communication" from whoever. Parameters are not like commandments from 
on high. You need to understand the parameterization process and the 
target problems in order to justify their application to your problem.

Mark