THEORY OF CORRELATION-EFFECTS FOR DIFFUSION IN A 2 SUBLATTICE STRUCTURE

The tracer diffusion correlation factor has been studied for a simple cubic lattice gas with two energetically inequivalent sublattices and sites restricted to accommodate a maximum of one atom. The model serve s as a paradigm for solids with site inequivalence but no algebraic fo rmulae have previously been derived and compared with available Monte Carlo simulation data. An expression based on a kinetic equation theor y which neglects the highest order in concentration fluctuations is sh own to lead to a good description of the simulation results. The time dependence of the associated time correlation function appears to be u nusually complex for diffusion iii a two sublattice system. (C) 1997 E lsevier Science Ltd. All rights reserved.