An elastoplastic model approach for the relaxation dynamics of active glasses

TL;DR

This paper introduces an active elastoplastic model to study the relaxation dynamics of active glasses, capturing key behaviors and revealing how activity influences plastic yielding and dynamic heterogeneity.

Contribution

It develops a novel active elastoplastic model incorporating activity effects, providing new insights into active glass relaxation dynamics and their underlying mechanisms.

Findings

Active yielding dominates relaxation dynamics.

Persistence of yielding direction influences heterogeneity.

Model aligns with known active glass behaviors at small activity.

Abstract

How activity affects the glassy dynamics is crucial for several biological processes. Furthermore, active glasses offer fascinating phenomenologies, extend the scope of equilibrium glasses, and can provide novel insights into the original problem. We introduce a family of novel approaches to investigating the relaxation dynamics of active glasses via an active elastoplastic model (EPM). These approaches describe the relaxation dynamics via local plastic yielding and can provide improved insights as we can study various aspects of the system separately. Activity enters the model via three crucial features: activity-mediated plastic yielding, activated barrier crossing, and persistent rotational dynamics of the yielding direction. We first consider a minimal active EPM that adds the effect of active yielding to a thermal EPM. We show that this active EPM captures the known results of active glasses within a reasonable parameter space. The results also agree well with the analytical results for active glasses when activity is small. The minimal model breaks down at very low temperatures where other effects become important. Looking at the broader model class, we demonstrate that whereas active yielding primarily dominates the relaxation dynamics, the persistence of yielding direction governs the dynamic heterogeneity in active glasses.