The atomic configurations of the a→ threading dislocation in GaN

The atomic structure of the 1/3 〈1 1 2 0〉 edge dislocation has been simulated with the Stillinger–Weber empirical potential which was previously modified to take into account the homopolar bonds, Ga–Ga and N–N. This dislocation is characterised by a multiple structure based on rings of 4, 8 or 5/7 atoms. This multiplicity is explained by considering the position of the origin of the displacements corresponding to the creation of the dislocation. These displacements are imposed according to the isotropic linear elasticity theory. The choice of the origin is equivalent to consider the nature, differently spaced, of the two {1 0 1 0} prismatic planes. The tips of these two planes form the dislocation cores: 5/7-atom ring for the less spaced planes and 4 or 8-atom ring for the more spaced planes.