Electronic structure of substoichiometric carbides and nitrides of titanium and vanadium

The Korringa-Kohn-Rostoker--coherent-potential-approximation (KKR-CPA) and the Korringa-Kohn-Rostoker--Green's-function (KKR-GF) methods are applied to study the electronic structure of substoichiometric TiCₓ, TiNₓ, VCₓ, and VNₓ. The introduction of vacancies in the nonmetal sublattice influences the electronic structure of all these compounds in a similar way: an additional sharp ``vacancy peak'' appears in the density of states, which, with increasing vacancy concentration, is broadened and shifted to higher energies. The Fermi energy is generally lowered by the introduction of vacancies.