Role of generalized-gradient approximation in structural and electronic properties of bulk and surface ofβ-GaN and GaAs

Abstract
Using the first-principles pseudopotential approach, we have performed calculations of the total energy, atomic structure, and chemical bonding for the bulk and surfaces of GaAs and cubic GaN to assess the role of the generalized gradient approximation (GGA) for the exchange-correlation energy. Our calculations show that the combined effect of nonlinear core correction and GGA is responsible for significant changes in the structural parameters and electronic band structure of the (001) surface, regardless of the ionicity of the compound studied, but not for bulk or the nonpolar (110) surface.