Tracer correlation factors in the random alloy

An extensive Monte Carlo study has been made of tracer correlation factors in simple cubic, bcc and fee binary random alloys. Contrary to the findings of much of the earlier Monte Carlo work, where vacancy jump sequences were much too short, we found that generally Manning's diffusion kinetics formalism (Manning, J. R., 1968, Diffusion kinetics for Atoms ill Crystals; 1971, Phys. Rev. B, 4, 1111) provides only a fairly rough approximation for the tracer correlation factors except when the exchange frequency ratio is close to unity. It is found that the Holdsworth, P. C. and Elliott, R. J. (1986, Phil. Mag. A, 54, 601) kinetics formalism performs much better than Manning's over a wide range of exchange frequency ratios and, for the slow diffuser, is almost exact. The kinetics Formalism of Moleko, L. K., Allnatt, A. R., and Allnatt, E. L., (1989, Phil. Mag. A, 59, 141) performs even better, with essentially exact agreement for the slow diffuser, and excellent agreement for the faster diffuser except for extreme values of the exchange frequency ratio.