Existence of a vacancy band in electronic structures of niobium metal compounds

Abstract
The existence of a vacancy band in a series of niobium metal compounds, NbO, NbN and NbC, has been established by calculations using the DV-Xα cluster method. The vacancy band originating from the anion vacancies appears below the Fermi level. This band is mainly occupied by the Nb-4d electrons. Such an enhancement in the partial density of states of Nb-4d below the Fermi level is perhaps related to the stability of these compounds with a large number of vacancies.