Electronic structure of vacancies in refractory compounds and its influence on Tsub(c)

The electronic structure of a non-metal vacancy in cubic NbC and VN is investigated using the SCF-cluster approximation. Self-consistent charge densities are obtained for the solid with perfect order as well as with a vacancy in an unrelaxed lattice. Partial local densities of states and electron-phonon parameters are evaluated and found to be influenced by the presence of a vacancy even at more distant atoms. The superconducting transition temperature as a function of the vacancy concentration is calculated and agrees well with experimental values. (author)