The MM3 molecular mechanics program calculates a fair representation o
f hydrogen bonding interactions, but to improve the MM3 hydrogen bond
potential, a directional term has been added to the hydrogen bonding f
unction. The resulting total function was reoptimized. Comparisons of
the hydrogen bonding potential functions from ab initio, the original
MM3, the current MM3(92) force field and the reoptimized MM3 force hel
d MM3(94) for a variety of C,N,O systems are described.