Abstract
The electronic mass enhancement λk on the Fermi surfaces of Cu and Nb is expanded in various basis sets. In particular, orthogonal polynomials (‚Fermi surface harmonics’︁) are constructed in the velocity vector components (FSH(v)), in the wave vector components (FSH(k)) and the cubic harmonics (CH). The results indicate that the set FSH(k) gives better convergence than the sets FSH(v) or CH.