I have been having a hard time figuring out where to get the OPLS dihedral parameters for lammps. I see in the OPLS dihedral form used by lammps, one specifies the V1 V2 V3 and V4 in the dihedral_coeff command. However, in all the OPLS parameter sets I have looked at, the one given in tinker being what I think is close to the latest version of OPLS (http://dasher.wustl.edu/ffe/distribution/params/oplsaa.prm
), I only see a mention of what I believe to be V1 V2 V3 and f1 f2 f3 where the latter are the phase angle offsets. The Watkins paper cited in the lammps manual only provides parameters for perfluouroalkanes, so I was wondering where I need to go to obtain these parameters for other molecules, or is there some conversion between the V1 V2 V3 f1 f2 f3 to the V1 V2 V3 V4 sets that I am missing.