LAMMPS
LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) [1] has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) and coarse-grain systems. It can be used to model atoms or, more generically, as a parallel particle simulator at the mesoscale or continuum levels. LAMMPS runs on single-processor machines or in parallel using message-passing techniques and a spatial-decomposition of the simulation domain. The code is designed to be easy to modify or extend with new functionality.
Force fields
LAMMPS can accomodate the following force fields [2]: CHARMM, AMBER, and DREIDING.