The Martini force field: Different flavors for molecular simulations

The MARTINI forcefield is a coarse grained forcefield suited for molecular dynamics simulations of biomolecular proceses beyond the microsecond time scale. The forcefield has been parametrized in a systematic way, based on the reproduction of partitioning free energies between polar and apolar phases of a large number of chemical compounds. The model uses a four-to-one mapping, i.e. on average four heavy atoms are represented by a single interaction center. In order to keep the model simple, only four main types of interaction sites are defined: polar (P), non-polar (N), apolar (C), and charged (Q). Each particle type has a number of subtypes, which allow for an accurate representation of the chemical nature of the underlying atomistic structure. Currently the force field is available for many lipids and surfactant molecules, including cholesterol, and for all amino acids as well as for sugars and polymers.