[gmx-users] opls LJ combination rules

Markus O Kaukonen mokaukon at cc.helsinki.fi
Fri Dec 3 08:53:42 CET 2004

Dear All,

When reading OPLS author (jorgensen-JACS-v118-pp11225-11236-y1996,
below eq.1 ) the combination rules for LJ parameters is
sigma_ij=sqrt(sigma_i*sigma_j). This is not what Gromacs manual says
(eq. 4.7 in Gromacs-3.2 manual).

Is the formula for OPLS potential in gromacs as in

Are the phase angles f1, f2, f3 in torsion potential always zero in

I find these questions of some importance when using OPLSAA-gromacs
and hope someone who has done the gromacs coding could comment.

Or is the only way to 'look at the source code'.

Terveisin Markus

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