.. _ff: Interaction function and force fields ===================================== To accommodate the potential functions used in some popular force fields (see :ref:`ff`), |Gromacs| offers a choice of functions, both for non-bonded interaction and for dihedral interactions. They are described in the appropriate subsections. The potential functions can be subdivided into three parts #. *Non-bonded*: Lennard-Jones or Buckingham, and Coulomb or modified Coulomb. The non-bonded interactions are computed on the basis of a neighbor list (a list of non-bonded atoms within a certain radius), in which exclusions are already removed. #. *Bonded*: covalent bond-stretching, angle-bending, improper dihedrals, and proper dihedrals. These are computed on the basis of fixed lists. #. *Restraints*: position restraints, angle restraints, distance restraints, orientation restraints and dihedral restraints, all based on fixed lists. #. *Applied Forces*: externally applied forces, see chapterĀ :ref:`special`. .. toctree:: :maxdepth: 2 functions/nonbonded-interactions functions/bonded-interactions functions/restraints functions/polarization functions/free-energy-interactions functions/interaction-methods functions/long-range-electrostatics functions/long-range-vdw functions/force-field