Ideal glass states are not purely vibrational: Insight from randomly pinned glasses

TL;DR

This study uses simulations to show that ideal glass states involve localized excitations contributing to entropy, indicating that glasses are not purely vibrational but have complex internal dynamics.

Contribution

It demonstrates that even in ideal glass states, localized excitations influence thermodynamics and dynamics, challenging the view of glasses as purely vibrational solids.

Findings

Localized excitations exist in ideal glasses.

Thermodynamics and dynamics are coherently linked in glasses.

Glasses exhibit nonlinear internal dynamics.

Abstract

We use computer simulations to probe the thermodynamic and dynamic properties of a glass-former that undergoes an ideal glass-transition because of the presence of randomly pinned particles. We find that even deep in the equilibrium glass state the system relaxes to some extent because of the presence of localized excitations that allow the system to access different inherent structures, giving thus rise to a non-trivial contribution to the entropy. By calculating with high accuracy the vibrational part of the entropy, we show that also in the equilibrium glass state thermodynamics and dynamics give a coherent picture and that glasses should not be seen as a disordered solid in which the particles undergo just vibrational motion but instead as a system with a highly nonlinear internal dynamics.