Overlap fluctuations in glass-forming liquids

TL;DR

This paper investigates how static overlap fluctuations in glass-forming liquids evolve near the glass transition, revealing non-Gaussian behavior and a first-order phase transition induced by a thermodynamic field.

Contribution

It demonstrates the emergence of non-Gaussian overlap fluctuations and the existence of a thermodynamic phase transition in glass-forming liquids approaching the glass transition.

Findings

Overlap fluctuations become non-Gaussian near the transition

A thermodynamic field induces a first-order phase transition

Structural fluctuations change profoundly near the glass transition

Abstract

We analyse numerically thermal fluctuations of the static overlap between equilibrium configurations in a glass-forming liquid approaching the glass transition. We find that the emergence of slow dynamics near the onset temperature correlates with the development of non-Gaussian probability distributions of overlap fluctuations, measured using both annealed and quenched definitions. Below a critical temperature, a thermodynamic field conjugate to the overlap induces a first-order phase transition, whose existence we numerically demonstrate in the annealed case. These results establish that the approach to the glass transition is accompanied by profound changes in the nature of thermodynamic fluctuations, deconstructing the view that glassy dynamics occurs with little structural evolution.