An extensive study was made of diffusion in liquid Si and Ge using empirical Stillinger-Weber potentials. A numerical algorithm was used in which the three-body part of the Stillinger-Weber potential was decomposed into products of two-body potentials; thus permitting the study of large systems. One choice of Stillinger-Weber parameters agreed very well with observed liquid Ge structure factors. The diffusion coefficient at the melting point was found to be approximately 6.4 x 10-5cm2/s for liquid Si; in good agreement with previous calculations. It was about 4.2 x 10-5 or 4.6 x 10-5cm2/s for two models for liquid Ge. In all cases, the diffusivity could be fitted to an activated temperature dependence, with activation energies of about 0.42eV for liquid Si and 0.32 or 0.26eV for two models for liquid Ge, as deduced from either the Einstein relation or from a Green-Kubo-type integration of the velocity autocorrelation function. The diffusivity for Si impurities in liquid Ge was found to be very similar to the self-diffusion coefficient of liquid Ge.

Empirical Molecular-Dynamics Study of Diffusion in Liquid Semiconductors. Yu, W., Wang, Z.Q., Stroud, D.: Physical Review B, 1996, 54[19], 13946-54