Universal Density of Low Frequency States in Silica Glass at Finite Temperatures

Silvia Bonfanti, Roberto Guerra, Itamar Procaccia, Stefano Zapperi

Published 2021-09-20Version 1

The theoretical understanding of the low-frequency modes in amorphous solids at finite temperature is still incomplete. The study of the relevant modes is obscured by the dressing of inter-particle forces by collision-induced momentum transfer that is unavoidable at finite temperatures. Recently, it was proposed that low frequency modes of vibrations around the thermally averaged configurations deserve special attention. In simple model glasses with bare binary interactions, these included quasi-localized modes whose density of states appears to be universal, depending on the frequencies as $D(\omega) \sim \omega^4$, in agreement with the similar law that is obtained with bare forces at zero temperature. In this Letter, we report investigations of a model of silica glass at finite temperature; here the bare forces include binary and ternary interactions. Nevertheless we can establish the validity of the universal law of the density of quasi-localized modes also in this richer and more realistic model glass.