Mobility-induced phase separation in a binary mixture of active Brownian particles

TL;DR

This study uses Brownian dynamics simulations to explore how activity-induced interactions lead to phase separation in a binary mixture of active particles, revealing liquid-like high-density states with disordered structures.

Contribution

It demonstrates that activity can induce phase separation in binary mixtures, resulting in disordered high-density states that are distinct from monocomponent systems.

Findings

High-density states are spatially disordered in binary mixtures.

Both low- and high-density states exhibit diffusive behavior.

High-density states are liquid-like despite being dense.

Abstract

In this paper, we report a Brownian dynamics simulation of the mobility-induced phase separation which occurs in a two-dimensional binary mixture of active soft Brownian particles, whose interactions are modeled by non-additive Weeks-Chandler-Andersen potentials inspired in Lennard-Jones potentials used for glass-forming passive mixtures. The analysis of structural properties, such as the radial distribution functions and the hexatic order parameter, shows that the high-density coexisting state in the binary case is spatially disordered, unlike the solid-like state observed for the monocomponent system. Characterization of the mean-square displacement of the active particles shows that both the low- and high-density coexisting states have diffusive behavior for long times. Thus, the high-density coexisting states are liquid-like in the binary cases. Moreover, diffusive behavior is also observed in the high-density solid-like state for the monocomponent system, which is driven by the presence of active topological defects.