Vibrational states and disorder in continuously compressed model glasses

TL;DR

This study investigates how elastic heterogeneities influence vibrational eigenvectors in amorphous materials under pressure, linking structural disorder to vibrational properties and the boson peak phenomenon.

Contribution

It provides a detailed numerical analysis connecting elastic heterogeneities and vibrational eigenvectors in compressed amorphous solids, including silica glass.

Findings

Vibrational eigenvectors are affected by elastic heterogeneities.

The boson peak pressure dependence mirrors that of transverse waves.

Vibrational properties correlate with structural disorder.

Abstract

We present in this paper a numerical study of the vibrational eigenvectors of a two-dimensional amorphous material, previously deeply studied from the point of view of mechanical properties and vibrational eigen-frequencies [7-10]. Attention is paid here to the connection between the mechanical properties of this material in term of elastic heterogeneities (EH), and how these inherent heterogeneous structures affect the vibrational eigenvectors and their plane waves decomposition. The systems are analysed for different hydrostatic pressures, and using results from previous studies, a deeper understanding of the boson peak scenario is obtained. The vibrational spectrum of a continuously densified silica glass is also studied, from which it appears that the pulsation associated with the boson peak follows the same pressure dependence trend than that of transverse waves with pulsation associated with the EH characteristic size.