Defect energetics in MgO treated by first-principles methods.

Abstract

Ab initio total-energy calculations have been performed on a parallel computer to study the formation and migration energies of cation and anion vacancies in MgO. The calculations are made in the framework of density functional and pseudopotential theory, using the supercell method, with the valence orbitals expanded in plane waves. The relaxed ground state is determined by conjugate-gradients minimization of the total-energy functional with respect to the plane-wave coefficients of occupied orbitals. The calculated defect energies are shown to be in remarkably close agreement with experiment and with values obtained from empirical modeling. We present results for the electron distribution surrounding the vacancies that show that the distortion induced in the oxygen ions is more complex than has previously been thought.