MacroModel contains a variety of force fields. Which is best for my purpose?
Each of the MacroModel force fields has strengths, but in general, the most complete and well parameterized force fields are MMFF, OPLS_2001, and OPLS_2005. The other force fields are routinely used for special situations; for example, when using united atoms (AMBER*) or when reproducing or extending previous results. Although there are no absolute guidelines available for choosing the most appropriate MacroModel force field for a given molecular modeling application, the following generalizations are reasonable: OPLS_2005: Probably the best available force field for condensed-phase simulation of peptides. Work to develop parameterization that will include broader classes of drug-like molecules is ongoing. OPLS_2001: Is a solid implementation of the OPLS-AA force field. GB/SA solvation energies are good. MMFF: An excellent force field for biopolymers and many organic molecules that do not have parameters in other force fields. The MMFFs extension of this force field is also supported.
