Study of extended defects in molecular crystals by the atom–atom potential method. 1. Slip planes in the anthracene crystal

Abstract

The atom–atom potential method was used to calculate the relative facility of slip in various directions in the (001), (010), (100) and (201) crystallographic planes in the anthracene crystal. A uniform slip of one semi-infinite half of the crystal against the second such half was considered. Three quantities were calculated as functions of slip : the lattice energy of the whole crystal, the energy of interaction between the two half-crystals, and the specific surface energies of various slip planes.

The results of the calculations were compared with reported dislocation densities. It was found that the slip direction with the lower energy profiles correspond to the more frequently observed Burgers vector direction of the dislocations. Several fault structures of relatively low energies were found, suggesting possible mechanisms of dissociation of full dislocations into partials.

The possible applicability of the procedure as an approach to the calculation of the strain energies and geometries of dislocations in molecular crystals was considered.