By using molecular statics methods, calculations were made of the variation in the excess energy that was associated with the gradual approach of an edge dislocation to the free surface of a crystal. The calculations used a phenomenological potential for Al, and the procedure permitted the investigation of both the extended and perfect configurations of the dislocation core. An estimate of the energy which was required for the introduction of a dislocation into a thin film was thereby obtained. The calculations showed that a relaxed surface step and a dislocation near to a free surface corresponded to almost equal excess energy values. It was noted that anelastic contributions were crucially important at short surface-dislocation distances, and led to the emergence of the dislocation. The calculations suggested that emergence could be considered to be a general trend for face-centered cubic metals. Upper limits were placed on the external stress which was needed for the nucleation of a dislocation at the surface of a thin film.

Atomistic Calculation of the Interaction between an Edge Dislocation and a Free Surface. A.Aslanides, V.Pontikis: Philosophical Magazine Letters, 1998, 78[5], 377-83