Theory of the pressure dependence of the electronic and optical properties of trigonal Te

Using a self-consistent pseudopotential formalism based on realistic pseudopotentials of the free ion and atom, the influence of hydrostatic pressure on the electronic structure and the optical spectra of trigonal Te is investigated. The pressure derivative of the fundamental gap is found to be in good agreement with experimental results. The joint density of states, ${\epsilon }_1$ and ${\epsilon }_2$, energy-loss function, reflectivity, and absorption coefficient are calculated from 0 to 13 eV. Very good agreement is obtained with experimental spectra. The very strong pressure-induced enhancement of the reflectivity can be reproduced. The anisotropy anomaly in the reflectivity at high energies is explained and traced to distinct transitions in the Brillouin zone. Predictions are made about the pressure dependence of the optical spectra above 4 eV. Finally, selfconsistent charge densities and the electronic density of states are also presented.