Static self-induced heterogeneity in glass-forming liquids: Overlap as a microscope

TL;DR

This paper introduces a numerical method to visualize and quantify the static heterogeneity in glass-forming liquids by analyzing local overlap fluctuations, providing insights into the thermodynamics of glass transition.

Contribution

It presents a novel local probe based on overlap statistics in mesoscopic cavities to measure self-induced heterogeneity and surface tension in glass-forming liquids.

Findings

First direct visualization of self-induced heterogeneity.

Quantitative estimate of surface tension between amorphous states.

Analysis of local configurational entropy fluctuations.

Abstract

We propose and numerically implement a local probe of the static self-induced heterogeneity characterizing glass-forming liquids. The method relies on the equilibrium statistics of the overlap between pairs of configurations measured in mesoscopic cavities with unconstrained boundaries. By systematically changing the location of the probed cavity, we directly detect spatial variations of the overlap fluctuations. We provide a detailed analysis of the statistics of a local estimate of the configurational entropy and we infer an estimate of the surface tension between amorphous states, ingredients that are both at the basis of the random first-order transition theory of glass formation. Our results represent the first direct attempt to visualize and quantify the self-induced heterogeneity underpinning the thermodynamics of glass formation. They pave the way for the development of coarse-grained effective theories and for a direct assessment of the role of thermodynamics in the activated dynamics of deeply supercooled liquids.