Self-consistent band theory of the Fermi-surface, optical, and photoemission properties of copper

A two-parameter self-consistent theory of the electronic structure of copper is presented. The first parameter, the exchange coefficient α appearing in Slater's Xα theory, is adjusted so that the ground-state energy bands generate the measured Fermi surface. The second parameter, the electron-electron contribution to the effective electron mass m* appearing in the Sham-Kohn local-density theory of excitations, is adjusted to optical-absorption data. The theory treats all electrons identically and provides a more accurate unified interpretation of Fermi-surface, optical-absorption, and photoemission data than previously obtained. We show that the transition probabilities (momentum matrix elements), while their inclusion is necessary for a convincing description of ε2(ω), can for the most part be assumed constant in the calculation of photoemission spectra. Comparison with the Chodorow potential shows that it gives excellent results for the d bands, but leads to excited-state energies which are approximately 7% too low. A detailed description is given of our computational procedures, including the generation of momentum matrix elements, k→•p→ extrapolation, k→-space integration procedures and convergence tests, as well as our procedure for constructing photoemission energy distributions. © 1975 The American Physical Society.