BULK ELECTRONIC-STRUCTURE OF SIO2

The electronic structures of crystalline and amorphous SiO2 are examined via the tight-binding method. A new tight-binding Hamiltonian, fit to experiment and to the pseudopotential band structure of α quartz, is used to calculate densities of states for both α quartz and an SiO2 Bethe lattice. These are shown to compare favorably with x-ray photoemission spectra of α quartz and amorphous SiO2. The computational results are analyzed qualitatively using the bond-orbital approach. For both crystalline and amorphous SiO2 it is suggested that oxygen 2s character in the lower conduction bands may be necessary to account for the large gap. Local symmetries of the lone-pair-like bands of possible relevance to the optical properties are discussed. © 1979 The American Physical Society.