The effect of nonorthogonality in the density of states of some metallic disordered systems

The effect of nonorthogonality and disorder in several metallic systems has been studied within the tight-binding approximation. Liquid transition metals, supercritical alkali metals and impurity bands in doped semiconductors were considered. Calculations were performed considering the interactions between all pairs of atoms, neglecting and including the nonorthogonality between the atomic orbitals. It is concluded that the inclusion of the nonorthogonality is important in all these materials except the 3d liquid transition metals. The effect of increasing the disorder is qualitatively analogous to that of decreasing the number of neighbours in ordered, periodic structures. (author)