Minimax CHARMM FF restrictions



Dihedral angle (torsion) potential:
Multiple dihedral terms are limited to a maximum of 5 terms per dihedral angle. The harmonic restoring potential for dihedrals is not implemented, terms with periodicity 0 are treated as an additive constant.
Improper dihedral angle potential:
Only the harmonic restoring potential is implemented. Terms with non-zero periodicity are not supported, and will lead to program termination.
Hydrogen bond potential: not implemented.

Extended electrostatics (multipole expansion of long range electrostatic interactions): not implemented.

Nonbonded energy cutoff:

The nonbonded energy cutoff is always atom based. Charge group based cutoff is not implemented. If a cutoff is used, the nonbonded energy terms will be modified by either switching or shifting. Forced based shifting and switching are not implemented.


A.Widmer, NIBR/CPC/CSG-SB