[gmx-users] Dihedral form

[Laura Leay]

All,

I would like to parameterise the Dreiding force field for use with Gromacs. One thing I am not sure about is how to parameterise the dihedrals

The Dreiding paper has the form;

 E= 0.5k { 1 - cos[ n( phi - phi_o)]}

However I cannot find this form in the Gromacs manual. The closest I can find in the Gromacs manual is:

E = k [ 1 + cos(n*phi - phi_s) ]


Does anyone know of a way to use the Dreiding form in Gromacs, or to convert to a form that is more suitable for use with Gromacs?

Many thanks,
Laura