Relaxation in a Phase-separating Two-dimensional Active Matter System with Alignment Interaction

TL;DR

This study uses computer simulations to analyze pattern formation, growth, and aging in a two-dimensional active matter system with alignment interactions, revealing power-law behaviors and effects of temperature on phase separation.

Contribution

It introduces a detailed simulation study of active matter with Vicsek-like activity combined with Lennard-Jones interactions, focusing on morphology, growth, and aging.

Findings

Growth and aging follow power-law time dependence.

Exponents are comparable to passive systems and vary with temperature.

Active matter exhibits similar scaling behavior to passive phase separation.

Abstract

Via computer simulations we study kinetics of pattern formation in a two-dimensional active matter system. Self-propulsion in our model is incorporated via the Vicsek-like activity, i.e., particles have the tendency of aligning their velocities with the average directions of motion of their neighbors. In addition to this dynamic or active interaction, there exists passive inter-particle interaction in the model for which we have chosen the standard Lennard-Jones form. Following quenches of homogeneous configurations to a point deep inside the region of coexistence between high and low density phases, as the systems exhibit formation and evolution of particle-rich clusters, we investigate properties related to the morphology, growth and aging. A focus of our study is on the understanding of the effects of structure on growth and aging. To quantify the latter we use the two-time order-parameter autocorrelation function. This correlation, as well as the growth, is observed to follow power-law time dependence, qualitatively similar to the scaling behavior reported for passive systems. The values of the exponents have been estimated and discussed by comparing with the previously obtained numbers for other dimensions as well as with the new results for the passive limit of the considered model. We have also presented results on the effects of temperature on the activity mediated phase separation.