A TIGHT-BINDING MOLECULAR-DYNAMICS SIMULATION OF THE MELTING AND SOLIDIFICATION OF SILICON

The melting of solid silicon and the cooling of liquid silicon are inv estigated using molecular dynamics. Both the Stillinger-Weber (SW) pot ential and the tight-binding bond model are used to calculate the forc es. The electrical properties are investigated using an empirical pseu dopotential method with a plane wave basis. The temperature at which t he solid becomes unstable and passes to the liquid phase is found to b e about 2300 K. The dependence of this temperature on cell size is inv estigated. On cooling, there are changes in some of the properties of the liquid: the energy per particle decreases, the diffusion constant decreases, and the low-frequency electrical conductivity decreases sli ghtly as the temperature decreases. Between 1180 K and 980 K the liqui d undergoes a transition to a glassy phase. There are large changes in the pair correlation function, the SW three-body energy distribution, the diffusion constant, the density of electron single-particle state s and the electrical conductivity. All of these changes are consistent with increased tetrahedral bonding.