SEMICONDUCTOR BAND STRUCTURES AT ZERO PRESSURE

Ab initio converged total-energy studies, and calculations of electronic states, pressure derivatives, and effective masses have been performed for the semiconductors Si, Ge, GaAs, AlAs [using the local-density approximation (LDA) pseudopotential plane-wave method] as a function of cell volume. The calculated pressure derivatives of electronic states agree well with existing experimental data. At zero pressure, the overall description of energy bands is found to be improved, both for valence and conduction, as compared to the commonly assumed band structure at the experimental volume. In particular, Ge is correctly predicted to be an indirect-gap semiconductor, and calculated effective masses are found to be in good agreement with experiment at zero pressure. Further, quasiparticle energies computed with the LDA bands at zero pressure agree well with experimental data for all materials.