Low-temperature properties of a model glass

Abstract

We study the low-temperature properties of glasses in a model consisting of elastic dipoles placed randomly in an elastic continuum. We use Monte Carlo annealing to find glassy minimum-energy states and then determine the density of states for small angular oscillations of the dipoles. The coupling of these modes to the phonon strain fields is shown to lead to a frequency-dependent velocity shift and lifetime for the phonons. We find a bump in C/${\mathrm{T}}^3$ and a plateau in the thermal conductivity, in quantitative agreement with experimental data for the orientational glass KBr:KCN.