Spontaneous Segregation of Self-Propelled Particles with Different Motilities

TL;DR

This study uses simulations to explore how mixtures of self-propelled and passive rods in two dimensions spontaneously segregate, forming diverse structures influenced by propulsion, density, and composition, revealing underlying mechanisms and fluctuation phenomena.

Contribution

It introduces a detailed analysis of segregation mechanisms in active-passive rod mixtures, highlighting the role of collision frequency differences and clustering effects.

Findings

Segregation occurs spontaneously based on propulsion and density.

Collision frequency differences drive segregation.

Giant number fluctuations observed at high propulsion velocities.

Abstract

We study mixtures of self-propelled and passive rod-like particles in two dimensions using Brownian dynamics simulations. The simulations demonstrate that the two species spontaneously segregate to generate a rich array of dynamical domain structures whose properties depend on the propulsion velocity, density, and composition. In addition to presenting phase diagrams as a function of the system parameters, we investigate the mechanisms driving segregation. We show that the difference in collision frequencies between self-propelled and passive rods provides a driving force for segregation, which is amplified by the tendency of the self-propelled rods to swarm or cluster. Finally, both self-propelled and passive rods exhibit giant number fluctuations for sufficient propulsion velocities.