Atomic forces from electronic energies via the Hellmann-Feynman theorem, with application to semiconductor (110) surface relaxation

A method has been devised for computer simulations of covalently bonded systems, such as semiconductors. The method uses noncentral and nonlocal effective potentials generated from the electronic structure via the Hellmann-Feynman theorem. As an elementary example, the method is applied to the time-dependent relaxation of the (110) surfaces of various III-V and II-VI compound semiconductors, starting from an ``ideal'' unrelaxed surface.