Atomic transport properties of silicon melt at high temperature

Abstract

Atomic transport properties, in particular, the self-diffusion and shear viscosity of silicon melt at high temperatures near the melting point are studied employing classical molecular dynamics simulations based on multiple empirical interatomic potentials. We find that the diffusion and viscosity coefficients of silicon melt predicted by the empirical potentials follow the Stokes-Einstein (SE) relation although both of which deviate from the experimental values. The discrepancy between the calculated and experimental diffusion coefficients are analyzed using the SE relation. We demonstrate that the discrepancy is partially attributed to the underestimation of the self-diffusion coefficients by the empirical potentials. Further, we analyze the microstructure of the melt based on several topological techniques and confirm that the (over) underestimation of the (viscosity) diffusion coefficients is caused by the overemphasis of the covalent bonding in the silicon melt.