An electron counting modification to potentials for covalently bonded surfaces

The surface structure of covalently bonded semiconductor materials undergoes reconstructions that are driven by electron redistribution between dangling and interatom bonds. Conventional interatomic potentials account for neither this electron redistribution nor its effects upon the atomic structure of surfaces. We have utilized an electron counting analysis to develop a surface interatomic potential that captures many of the effects of electron redistribution upon the surface structures of covalently bonded materials. The contributions from this potential decrease rapidly to zero beneath a surface. As a result, this surface potential can be added to many interatomic potentials for covalent materials without affecting its predictions of bulk properties such as cohesive energy, lattice parameters, and elastic constants. We demonstrate the approach by combining the surface potential with a recently proposed bond order potential and use it in a molecular statics simulation of the atomic reconstruction of a w...