Study of potentials suitable for band structure calculations of the noble metals: I. Copper

As a first stage in the investigation of suitable potentials for the noble metals, the energy bands and Fermi surface of copper have been calculated by the Green function method. The potentials of Herman and Skillman used by many workers are found to be unsuitable; the d bands are too narrow and too low and the Fermi surface does not contact the boundary of the Brillouin zone. Attempts to modify the potential between the muffin-tin spheres failed to improve the results. The amount of exchange energy included in a Gáspár-type potential is found to affect the band structure considerably. Satisfactory agreement with experimental and other theoretical results is nevertheless obtained if the exchange is reduced to about 30-40% of the amount proposed by Gáspár.