OPTICAL-PROPERTIES OF PDO AND PTO

We have calculated the anisotropic dielectric function for PdO and PtO using the linear-muffin-tin-orbital method in atomic-sphere-approxima tion. The optical matrix elements are explicitly included in the calcu lations and we find that they play a significant role in determining t he shape of the frequency dependence of the dielectric function and it s anisotropy. Our calculated dielectric functions for PdO are compared with the recent data of Weber et al. The agreement is good although t he calculations show more features than are observed experimentally an d give a band gap that is too small by about 0.6 eV. For PtO there are no experimental data available. We conclude that for these two transi tion-metal monoxides an itinerant description of the d states is appro priate.