The electronic structure of NbC and NbN

A self-consistent band-structure calculation has been performed for niobium carbide using the non-relativistic APW method and the X alpha exchange approximation. An analogous calculation already exists for NbN. Both band structures are fitted with a Slater-Koster LCAO scheme including overlap contributions. From a comparison of the two compounds a pronounced change in the non-metal p and niobium d interaction is found, which is discussed in connection with the binding mechanism, ESCA shifts and superconductivity. The X-ray emission spectra of NbC as computed from the present APW results agree well with experiments.