Self-Consistent Band Structure of Niobium at Normal and Reduced Lattice Spacings

Abstract

Self-consistent augmented-plane-wave energy-band calculations have been carried out for niobium for (a) normal lattice constant, $\ensuremath{\alpha}=1$ exchange, (b) normal lattice constant, $\ensuremath{\alpha}=\frac{2}{3}$ exchange, and (c) 5% reduced lattice constant, $\ensuremath{\alpha}=\frac{2}{3}$ exchange. At normal lattice constant, $\ensuremath{\alpha}=\frac{2}{3}$ exchange, an occupied $s\ensuremath{-}d$-band width of 0.387 Ry is found, in very good agreement with both $L$ and $M$ soft-x-ray emission experiments. The calculated density of states at the Fermi energy is 28.2 states ${\mathrm{atom}}^{\ensuremath{-}1}$ ${\mathrm{Ry}}^{\ensuremath{-}1}$, corresponding to a McMillan enhancement factor of 1.6. The Fermi surface consists of hole ellipsoids centered at $N$, a large hole octahedron centered at $\ensuremath{\Gamma}$, and a multiply connected "jungle gym," similar to that calculated by Mattheiss. The largest difference between experimental and calculated areas is less than 15%.