The ab-initio energetics of oxides

We show that accurate predictions of the energetics and structure of point defects and surfaces in oxides can be made using ab-initio methods. The techniques used are density functional theory and pseudopotentials, with valence orbitals represented by a plane-wave expansion. Key features are that the calculations can readily be taken to complete convergence with respect to the size of the basis set and that forces can straightforwardly be calculated, so that defect and surface structures can be relaxed to equilibrium. The calculations have been performed using the new parallel code CETEP on massively parallel machines. Results are presented for the structure, energetics and electron distribution of vacancy and interstitial defects in MgO and Li2O, and the basal-plane surface of Al2O3.