The central role of thermal collective strain in the relaxation of structure in a supercooled liquid

TL;DR

This paper investigates how persistent displacements driven by thermal strains and local reorganizations influence the spatial heterogeneity of relaxation in supercooled liquids, revealing a new understanding of relaxation mechanisms.

Contribution

It introduces the concept that thermal collective strain, rather than particle movement frequency, governs structural relaxation heterogeneity in supercooled liquids.

Findings

Persistent displacements are key to relaxation heterogeneity.

Thermal strains and local reorganizations drive these displacements.

Relaxation time scales are linked to persistent displacement frequency.

Abstract

The spatial distribution of structural relaxation in a supercooled liquid is studied using molecular dynamics simulations of a 2D binary mixture. It is shown that the spatial heterogeneity of the relaxation along with the time scale of the relaxation is determined, not by the frequency with which particles move a distance pi/2kBragg, but by the frequency with which particles can achieve persistent displacements. We show that these persistent displacements are achieved through the coupled action of local reorganizations and unrecoverable thermal strains.