DL_POLY_2 can calculate three body interactions of the valence angle type [45]. These are not dealt with in the same way as the normal nonbonded interactions. They are generally very short ranged and are most effectively calculated using a link-cell scheme [23]. No reference is made to the Verlet neighbour list nor the excluded atoms list. It follows that atoms involved in the same three-body term can interact via nonbonded (pair) forces and ionic forces also. The calculation of the three-body terms is distributed over processors on the basis of the identity of the central atom in the bond. A global summation is required to specify the atomic forces fully.