Band theoretical studies of the electronic structure of oxides

The O^2? ion is a useful concept in ionic solids. Its electron density and large polarizability is well described by the Watson sphere model. The large variation in the electronic structure of oxides is illustrated by discussing the ionic MgO, the partly ‘covalent’ Cu₂O, and TiO and NbO which have defects with respect to the ideal NaCl structure. The variation in physical properties is shown for the oxides in the rutile structure ranging from the insulating TiO₂, the metallic RuO₂ to the ferromagnetic CrO₂. Electron densities, total energies and densities of states are used to study these materials.