Systematic Investigation of Self-Correlation Functions in Cubic Lattices; Mono- and Divacancy Mechanisms

The radial parts of the spatial self-correlation functions for a long-range diffusion of an isolated impurity via the monovacancy mechanism have been calculated for the monoatomic SC, BCC and FCC lattices within the encounter approximation, varying relevant parameters of the five-frequency model. An interaction of the impurity with the strongly bound divacancy has been studied for the FCC lattice within the encounter approximation and a high temperature limit. Simple expressions allowing to calculate the average number of impurity jumps per encounter Z and a scalar part of the self-correlation function Wo in terms of the five-frequency model parameters have been found.