Optical Constants of Metals

Abstract

A calculation of the interband contribution to the frequency dependent dielectric constant of metals is attempted based on a specific model. The frequency region near the threshold for the interband transitions is considered. Emphasis in the model is laid on the bending of the energy bands near the Brillouin zone boundary. Attention is focused on cases when the Fermi surface approaches the zone boundary or has a finite area of contact with it. The momentum matrix element is taken as constant, which is fitted so as to achieve agreement with the experimentally found dip in the dispersion curve of the extinction coefficient. The values of the square of the matrix element for the noble metals, copper, silver, and gold, which fit the experimental data of Schulz, are found to be in the ratio 0.43:0.69:0.69.