Fermi surface, fermi velocity, and electron--phonon interaction parameter in Nb

A Korringa--Kohn--Rostoker band structure formalism was used to fit extremal areas and effective masses obtained from de Haas--van Alphen measurements by using the appropriate cubic scattering phase shifts and their energy derivatives as disposable parameters. The resulting Fermi radii and velocities in the (100) and (110) planes are presented for all sheets of the Fermi surface. When the velocities are compared with the augmented-plane-wave calculations of Elyashar and Koelling [Phys. Rev., B15, 3620 (1977)], a local enhancement factor, lambda(k-vector), is deduced. 3 figures, 2 tables