Long-ranged Coulomb forces associated with charge transfer between anions and cations have been incorporated into the ab initio multicenter real-space molecular-dynamics method of Sankey and Niklewski, thereby extending the method to ionic species and heteropolar semiconductors. The (110) surface of GaAs is allowed to relax using this scheme, and adopts the well-accepted bond-rotation model, with the anions rotating 30.9° up out of the surface.

• Received 28 October 1991

DOI:https://doi.org/10.1103/PhysRevB.46.10464