Screw dislocation in a model sodium lattice

Abstract

The deformation stacking-fault energies and screw dislocation core structures in a model sodium lattice have been calculated for body-centred-cubic and hexagonal close-packed phases, using a fundamental effective ion-ion potential, the reliability of which has been established elsewhere. Particular emphasis is placed upon deviations from continuum elasticity, and it is shown that the use of linear elasticity theory over distances smaller than about ten lattice spacings can lead to serious error. It is shown that the screw dislocation core structures in b.c.c. and h.c.p. lattices have markedly different characteristics, and relative dislocation mobilities in the two phases are discussed in the light of these differences.