GROMACS is a versatile package for performing molecular dynamics, using Newtonian equations of motion, for systems with hundreds to millions of particles. GROMACS is primarily designed for biochemical molecules like proteins, lipids, and nucleic acids that have a multitude of complicated bonded interactions. But, since GROMACS is extremely fast at calculating the non-bonded interactions typically dominating simulations, many researchers use it for research on non-biological systems, such as polymers.
GROMACS supports all the usual algorithms expected from a modern molecular dynamics implementation.
The GROMACS code is maintained by developers around the world. The code is available under the GNU General Public License.