Hello, I am trying to port the GAFF force field from data/gaff.dat and data/gaff.prm to be read by another program (TINKER). However the parameter file of GAFF looks quite different than from MMFF94 or any of the other force fields. I was wondering if someone could explain to me the difference...
# atom properties
# fallback defs
# bond stretching parameters
# angle bending parameters
# empirical rule parameters (bond stretching)
# charge parameters
# empirical rule parameters (bend-stretch)
# out-of-plane parameters
# partial bond charge increments
# strech-bend parameters
# torsion parameters
# van der waals parameters
I just learned that GAFF's functional form of calculation is different, in calculating the above parameters. How difficult would it be to re-write those functions to accomodate GAFF params?