We present calculations related to the optical properties of PbSe and PbTe in an energy range from 0 to 26 eV based on recently developed band-structure models. The results are compared to measurements of the low-energy real part of the refractive index, to modulated reflectivity measurements for energies up to 6 eV, to energy-loss experiments for energies up to 20 eV, and to synchrotron-radiation reflectivity measurements involving transition from core $d$ levels. The agreement between the experimental data and theory can in some cases be improved by using orthogonalized-plane-wave functions in calculating transition-matrix elements. Differences between synchrotron-radiation reflectivity measurements and photoemission data are analyzed and discussed.

• Received 14 October 1974

DOI:https://doi.org/10.1103/PhysRevB.11.660