Atomistic breathing shell model calculations of dislocation core configurations in ionic crystals

Abstract

Abstract A study was undertaken to improve upon a previous rigid boundary atomistic calculation of the core properties of a/2〈110〉{110} edge dislocations in MgO. A flexible boundary method (Flex-II) based on linear elasticity theory and recently developed by Hoagland, Hirth and Gehlen (1976) was used to provide a more accurate determination of the boundary between the atomistic and the elasto-atomic regions. A central-force breathing shell model due to Sangster (1973) was used to take account of many-body effects in the interaction between ions. This marks the first application of the breathing shell model to the calculation of dislocation core configurations in ionic crystals. Within this model two potentials were used. One is due to Sangster (1973), the other is our previously developed Model 1 potential. The results obtained using the above potentials are analysed in terms of the stability of the dislocation symmetry type, the core displacement field, the volume of expansion and the total strain energy...