Distance Restraints

In DL_POLY_2 distance restraints, in which the separation between two atoms, is maintained around some preset value $r_0$ is handled as a special case of bond potentials. As a consequence distance restraints may be applied only between atoms in the same molecule. Unlike with application of the ``pure'' bond potentials, the electrostatic and van der Waals interactions between the pair of atoms are still evaluated when distance restraints are applied. All the potential forms of the previous section are avaliable as distance restraints, although they have different key words:

1. Harmonic potential: (-hrm)
2. Morse potential: (-mrs)
3. 12-6 potential bond: (-126)
4. Restrained harmonic: (-rhm)
5. Quartic potential: (-qur)

In DL_POLY_2 distance restraints are handled by the routine BNDFRC.