Band structure and optical properties of NiO. I. Band structure calculations

Abstract

A band structure calculation using well localised orbitals obtained in a self-consistent manner has been performed on NiO. The localisation of the orbitals allows the treatment of both the valence and the lowest conduction bands by the tight-binding method. The details of the crystal potential are presented. The charge densities calculated from the crystal one-electron function show the ionic nature of the compound and reveal the deviation from the perfect ionicity (ionicity 1.65). The asphericity of the nickel ion resulting from the cubic crystal field appears clearly. The crystal-field parameter Delta associated with the difference in the average energies of the eg and t2g bands compares well with the experimental value and is mainly due to the covalency.