Lifetimes and Lengthscales of Structural Motifs in a Model Glassformer

TL;DR

This study identifies and analyzes the lifetimes and spatial organization of local structural motifs in a model glassformer, revealing correlations between static structures and slow particle dynamics.

Contribution

It introduces a new method to identify local motifs and characterizes their lifetimes and networks, linking static structure to dynamics in a glassformer.

Findings

11A clusters have longer lifetimes than other motifs

Long-lived clusters form ramified networks correlated with slow particles

Structural lengthscale grows slower than dynamical lengthscale upon cooling

Abstract

We use a newly-developed method to identify local structural motifs in a popular model glassformer, the Kob-Andersen binary Lennard-Jones mixture. By measuring the lifetimes of a zoo of clusters, we find that 11-membered bicapped square antiprisms, denoted as 11A, have longer lifetimes on average than other structures considered. Other long-lived clusters are similar in structure to the 11A cluster. These clusters group into ramified networks that are correlated with slow particles and act to retard the motion of neighbouring particles. The structural lengthscale associated with these networks does not grow as fast as the dynamical lengthscale $\xi_4$ as the system is cooled, in the range of temperatures our molecular dynamics simulations access. Thus we find a strong, but indirect, correlation between static structural ordering and slow dynamics.