Nonparametrized calculation of the electronic and vibrational structure of amorphousSiOx

A nonparametrized calculation of both the electronic and vibrational structures of ${\mathrm{SiO}}_{\mathit{x}}$ for the complete range of oxygen concentration is presented. The equilibrium atomic geometries, charge distributions, and force constants between the atoms are calculated from first principles. It is found that the equilibrium distance and force constants between silicon and oxygen at the Si-O-Si bond depend on the local geometry and the oxygen concentration. The calculated photoemission response as well as the infrared absorption are in good agreement with experimental data.