Calculation of the imaginary part ϵ2( ω) of the dielectric function for TiN and ZrN

The interband contribution to epsilon 2 ( omega ) has been calculated for TiN and ZrN using the LCAO energy eigenvalues and eigenvectors, resulting from an LCAO fit to self-consistent APW band structures of these compounds. The k-dependence of the transition moments and lifetime broadening has been approximately taken into account. The theoretical epsilon 2 b ( omega ) curves are compared with experimental epsilon 2 b ( omega ) curves resulting from measurements of the optical constants. General agreement between theory and experiment is satisfactory, although some peaks in the theoretical curves are shifted by 0.5-1 eV to higher energies with respect to experimental findings.