Modification of the Peierls-Nabarro Model for Edge Dislocation Core

Abstract

The various assumptions implicit in the Peierls-Nabarro treatment of the core of an edge dislocation are critically reviewed. It is pointed out that the lattice barrier for dislocation motion, for the case where atom rows alternate along the slip plane, has twice the period and a much higher amplitude than for the case usually considered, where the atoms face each other across the slip plane. The resolution of this and other difficulties can be accomplished by arranging that the stress across the slip plane and its associated interaction potential be functions of the final, rather than the initial, position of each atom row. With this modification the lattice barrier has in every case the periodicity of the slip distance but the argument of the exponential factor controlling the height of the barrier is halved. The physical implication of this last result must await a more detailed treatment of the dislocation core than has been previously attempted.