Scaling description of the relaxation dynamics and dynamical heterogeneity of an active glass-forming liquid.

Abstract

Active glasses are a class of driven nonequilibrium systems that share remarkably similar dynamical behavior as conventional glass-formers in equilibrium. Glasslike dynamical characteristics have been observed in various biological systems from micro to macro length scales. As activity induces additional fluctuations in the system, studying how they couple with density fluctuations is an interesting question to address. Via extensive molecular dynamics simulations, we show that activity enhances density fluctuations more strongly than its passive counterpart. Increasing activity beyond a limit results in the sub-Arrhenius-type relaxation behavior in active glasses. We also propose a unified scaling theory that can rationalize the relaxation spectrum over a broad parameter range using the concept of an effective temperature. In particular, we show that our scaling theory can capture the dynamical crossover from super to sub-Arrhenius relaxation behavior by changing activity from small to large values. Furthermore, we present nontrivial system-size dependencies of the relaxation time at large activity limits that have not been found in any passive systems or even in active systems at small activities.