Band limits and the vibrational spectra of tetrahedral glasses

Abstract

The primary features of the Raman and infrared spectra of $A{X}_2$ tetrahedral glasses are associated with the edges of the vibrational bands calculated by Sen and Thorpe. The dominant Raman peak is assigned to a singular matrix element rather than a peak in the density of vibrational states. Simple expressions are developed which yield useful values of the vibrational force constants and intertetrahedral angles for vitreous Si${\mathrm{O}}_2$, Ge${\mathrm{O}}_2$, and Be${\mathrm{F}}_2$.