GROMOS

GROMOS is a force field for molecular dynamics simulation developed at the University of Groningen and the ETH Zurich. GROMOS is also the name for the molecular dynamics simulation package associated with this force field.

The GROMOS force field is a united atom rather than all-atom force field, which means that methyl groups are lumped together as one 'atom'. The force field was optimized with respect to the condensed phase properties of alkanes. The most widely used versions are GROMOS85 (37C4) and GROMOS96 (43A1, 43A2, 45A3).