Nucleation-induced transition to collective motion in active systems

TL;DR

This paper investigates how active elongated particles transition from disorder to collective motion, revealing a nucleation-driven phase change with critical cluster formation and power-law dynamics.

Contribution

It introduces a lattice gas model demonstrating a nucleation-based transition to polar order in active systems, highlighting the role of critical clusters.

Findings

Transition driven by critical nucleation clusters

Power-law divergence in ordering time

Coarsening process leads to polar order

Abstract

While the existence of polar ordered states in active systems is well established, the dynamics of the self-assembly processes are still elusive. We study a lattice gas model of self-propelled elongated particles interacting through excluded volume and alignment interactions, which shows a phase transition from an isotropic to a polar ordered state. By analyzing the ordering process we find that the transition is driven by the formation of a critical nucleation cluster and a subsequent coarsening process. Moreover, the time to establish a polar ordered state shows a power-law divergence.