FIRST-PRINCIPLES WANNIER FUNCTIONS OF SILICON AND GALLIUM-ARSENIDE

We present a self-consistent, real-space calculation of the Wannier fu nctions of Si and GaAs within density-functional theory. We minimize t he total-energy functional with respect to orbitals which behave as Wa nnier functions under crystal translations and, at the minimum, are or thogonal. The Wannier functions are used to calculate the total energy , lattice constant, bulk modulus, and the frequency of the zone-center TO phonon of the two semiconductors with the accuracy required in ab initio calculations. Furthermore, the centers of the Wannier functions are used to compute the macroscopic polarization of Si and GaAs in ze ro electric field. The effective charges of GaAs, obtained by finite d ifferentiation of the polarization, agree with the results of linear-r esponse theory.