Diffusion in a two-dimensional stoichiometric ordered alloy model was considered. Using a combination of Monte Carlo simulation and analytical developments, it was considered how the correlation factor for diffusion - as deduced from an isotope-effect experiment - was related to the actual correlation factor (all jumps included) and the correlation factor for effective diffusion by the six-jump-cycle mechanism. It was shown that the apparent correlation factor from an isotope effect experiment could deviate greatly from the actual correlation factor but extrapolated precisely to that for the six jump cycle when the long range order parameter approached unity. This clarifies the relationships between the various correlation factors in ordered alloys where inter-sublattice jumps predominate.

Diffusion Correlation Effects and the Isotope Effect in Intermetallic Compounds. I.V.Belova, G.E.Murch: Philosophical Magazine A, 2000, 80[9], 2073-81