Question about Ryckaert-Belleman torsion
Posted: Mon Jul 06, 2009 3:42 pm
The AMBER forcefield equations that we use have the same functional form as the PeriodicTorsionForce implementation in OpenMM. The improper torsion term is exactly the same, and I can incorporate it pretty easily. For proper torsions, we have the additional "multiplicity" variable with different parameters of barrier height and phase for each instance, the functional form is the same, except with a summation over the "multiplicity". In order to get the same effect from OpenMM, would I simply call PeriodicTorsionForce multiple times for each proper torsion (to emulate the multiplicity for each proper torsion), or would I need to use the RBTorsionForce somehow?