Density of States and Group Velocity Calculations for SiO2
Ab initio calculations of the electron group velocity for SiO2 are worked out. The conduction bands are calculated by means of two different techniques: Hartree-Fock (HF) and Density-Functional Theory (DFT). Eight energy bands have been used to calculate the density of states and group velocity for the energies of interest. Two different crystal structures of SiO2, built-up by the same fundamental unit, namely, the SiO4 tetrahedron, are investigated: they are the a-quartz, and the ß-cristobalite.
Fig. 3: GV vs. energy for a-quartz and ß-cristobalite. Solid lines: HF; dashed lines: DFT; circles: parabolic-band approximation.
KeywordsGroup Velocity Fundamental Unit Boltzmann Transport Equation SiO4 Tetrahedron Lower Conduction Band
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