Some aspects of the lattice dynamics of quartz

Abstract

An analysis has been made of published data on the frequencies of modes of vibration in quartz which have been measured by infra-red and Raman spectroscopy It is shown that the measurements are consistent with one another when account is taken of the fact that certain frequencies are split by the macroscopic electric fields associated with some of these modes All of the measured frequencies of the symmetric, antisymmetric and doubly degenerate modes have been used as data to determine the parameters of two new models for the lattice dynamics of quartz, one involving only short-range forces and the other including Coulomb interactions New measurements have been made by the method of inelastic neutron scattering of the frequencies of certain normal modes with wave vectors along the z axis of the crystal While both models give good qualitative agreement with these measurements, the model which includes Coulomb interaction is to be preferred since it agrees better with the spectroscopic data