It was recalled that an edge dislocation formed a step at the free surface upon leaving a crystal. In order to minimize the surface energy, the step gradually relaxed so that the elastic energy did not tend towards zero when the dislocation left. This resulted in a modification of the force upon the dislocation. Stress and energy calculations were performed which took account of the surface energy, and the resultant force upon a near-surface dislocation was determined.

Surface Step-Dislocation Transition and Nucleation at a Solid Free Surface. N.Junqua, J.Grilhé: Philosophical Magazine Letters, 1997, 75[3], 125-30