First-principles electronic structure of Si, Ge, GaP, GaAs, ZnS, and ZnSe. I. Self-consistent energy bands, charge densities, and effective masses

The self-consistent electronic structures of Si, Ge, and zinc-blende GaP, GaAs, ZnS, and ZnSe have been determined using the linear combination of Gaussian orbitals method with a local-density form of the exchange-correlation functional. A completely general form of the spatial dependence of the potential has been used to describe accurately the bonding character in the tetrahedral environment. Results are presented for the valence- and conduction-band energies, densities of states, effective masses, and charge densities. Comparisons are made with previous calculations and with photoemission measurements. A striking result is that the local-density theory underestimates the optical band gaps by approximately 30% or more, although the general conduction-band topology is good. The theoretical valence-band energies, charge densities, and electron and hole effective masses are also in good agreement with experiment. The energies and wave functions presented here are used to determine the optical properties of these materials in the following paper.