String-like Clusters and Cooperative Motion in a Model Glass-Forming Liquid

TL;DR

This study uses large-scale molecular dynamics simulations to analyze dynamical heterogeneities in a glass-forming Lennard-Jones liquid, revealing string-like cooperative motions that grow as the liquid cools.

Contribution

It demonstrates the formation of string-like clusters of mobile particles and characterizes their size distribution, linking these to polymerization-like behavior in a fragile glass-former.

Findings

Mobile particles form string-like clusters

String length increases with cooling

String length distribution resembles polymerization

Abstract

A large-scale molecular dynamics simulation is performed on a glass-forming Lennard-Jones mixture to determine the nature of dynamical heterogeneities which arise in this model fragile liquid. We observe that the most mobile particles exhibit a cooperative motion in the form of string-like paths (``strings'') whose mean length and radius of gyration increase as the liquid is cooled. The length distribution of the strings is found to be similar to that expected for the equilibrium polymerization of linear polymer chains.