ENVIRONMENT-DEPENDENT INTERATOMIC POTENTIAL FOR BULK SILICON

We use recent theoretical advances to develop a functional form for in teratomic forces in bulk silicon. The theoretical results underlying t he model include an analysis of elastic properties for the diamond and graphitic structures and inversions of nb initio cohesive energy curv es. The interaction model includes two-body and three-body terms which depend on the local atomic environment through an effective coordinat ion number. This formulation is able to capture successfully (i) the e nergetics and elastic properties of the ground-state diamond lattice, (ii) the covalent rehybridization of undercoordinated atoms, and (iii) a smooth transition to metallic bonding for overcoordinated atoms. Be cause the essential features of chemical bonding in the bulk are built into the functional form, this model promises to be useful for descri bing interatomic forces in silicon bulk phases and defects. Although t his functional form is remarkably realistic by the usual standards, it contains a small number of fitting parameters and requires computatio nal effort comparable to the most efficient existing models. In a comp anion paper, a complete parametrization of the model is given, and exc ellent performance for condensed phases and bulk defects is demonstrat ed.