[gmx-users] (no subject)

[rob yang]

Hello,
I've got a rudimentary question about gromos torsion parameters.

the gromos parameter is of the following format:
gd_1           2.67             -1.0            1
name      force constant  phase shift    multiplicity

>From the gromos paper, they've listed the torsion terms as 
K*[1+cos(phaseshift)cos(multiplicity*dihedral)

In a given .top file, one would parameterize the torsion of i, j, k, l by:
i j k l gd_1

so my question is that: does that mean for any torsion, there's only *one* 
term associated with it in the gromos forcefield? In contrast,  oplsa allows 
up to 6 terms in the following form:
V1/2(1+cos(x))+V2/2(1-cos(2x)) + V3/2(1+cos(3x))...