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

TL;DR

This paper demonstrates that the universal density of low-frequency quasi-localized vibrational modes, following a  power law, applies to silica glass at finite temperatures, extending previous findings from simpler models.

Contribution

It shows that the universal  law for low-frequency modes holds in a realistic silica glass model with complex interactions at finite temperature.

Findings

Universal  law confirmed in silica glass model

Validity of low-frequency mode universality extends beyond simple models

Results support the thermally averaged configuration approach

Abstract

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 {\em 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 work, 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.