Nonequilibrium glassy dynamics of self-propelled hard disks

TL;DR

This study investigates how self-propulsion influences the glass transition in dense systems of hard disks, revealing that activity shifts the critical density and affects the dynamics of the kinetic arrest.

Contribution

It introduces a two-dimensional model of self-propelled hard disks and characterizes the nonequilibrium glass transition influenced by activity.

Findings

Critical density for arrest increases with activity

Relaxation time diverges algebraically due to collective dynamics

Self-propulsion significantly alters the glass transition behavior

Abstract

We analyse the collective dynamics of self-propelled particles in the large density regime where passive particles undergo a kinetic arrest to an amorphous glassy state. We capture the competition between self-propulsion and crowding effects using a two-dimensional model of self-propelled hard disks, which we study using Monte-Carlo simulations. Although the activity drives the system far from equilibrium, self-propelled particles undergo a kinetic arrest, which we characterize in detail and compare with its equilibrium counterpart. In particular, the critical density for dynamic arrest continuously shifts to larger density with increasing activity, and the relaxation time is surprisingly well described by an algebraic divergence resulting from the emergence of highly collective dynamics. These results show that dense assemblies of active particles undergo a nonequilibrium glass transition which is profoundly affected by self-propulsion mechanisms.