Predicting surface free energies with interatomic potentials and electron counting

Abstract

Current interatomic potentials for compound semiconductors, such as GaAs, fail tocorrectly predict the ab initio calculated and experimentally observed surfacereconstructions. These potentials do not address the electron occupancies of dangling bondsassociated with surface atoms and their well established role in the formation oflow-energy surfaces. The electron counting rule helps account for the electrondistribution among covalent and dangling bonds, which, when applied to GaAs surfaces,requires the arsenic dangling bonds to be fully occupied and the gallium danglingbonds to be empty. A simple method for linking this electron counting constraintwith interatomic potentials is proposed and used to investigate energetics of theatomic scale structures of the GaAs(001) surface using molecular statics methods.