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

Abstract

In this paper, we report a Brownian dynamics simulation of the mobility-induced phase separation that occurs in a two-dimensional binary mixture of active soft Brownian particles, whose interactions are modeled by non-additive Weeks–Chandler–Andersen potentials inspired by 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. The 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. Therefore, 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.