[gmx-users] OPLS 1-4 interactions & intramolecular contributions to interaction energies ...
lindahl at csb.stanford.edu
Wed Jun 23 10:57:58 CEST 2004
> Can anybody tell me what the proper way of including
> 1-4 non-bonded interactions with the OPLSAA FF is ?
>> From previous messages in this list I gather that
> there seems to be no unique definition and the scaling
> factor for the 1-4 interactions including H-atoms seems
> to be different in different Gromacs versions. What is
> this factor in 3.2.1, what is it in 3.1.4 and which is the
> "correct" one ?
The scaling factors are defined in the force field files and not
hardcoded. They have always been 0.5 for both charge and LJ in OPLS-AA,
but other forcefields obviously have different serttings.
For OPLS-AA you should include 1,4 interactions between hydrogen atoms,
while many other forcefields prescribe you shouldn't (e.g. Gromos96).
This is controlled with a standard flag to pdb2gmx, but the default
value is set in the rtp file for the last couple of gromacs versions.
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