Estimation of the critical behavior in an active colloidal system with Vicsek-like interactions

TL;DR

This paper investigates the critical behavior of an active colloidal system with Vicsek-like interactions, revealing a phase transition with critical exponents similar to the 3d-Ising universality class, differing from passive models.

Contribution

It introduces a modified active Asakura-Oosawa model with Vicsek-like interactions and estimates its critical exponents, highlighting differences from passive systems.

Findings

Critical point not on the rectilinear diameter in active system

Estimated critical exponents $eta$ and $ u$ align with 3d-Ising universality

Phase separation depends on Vicsek-like interaction strength

Abstract

We study numerically the critical behavior of a modified, active Asakura-Oosawa model for colloid-polymer mixtures. The colloids are modeled as self-propelled particles with Vicsek-like interactions. This system undergoes phase separation between a colloid-rich and a polymer-rich phase, whereby the phase diagram depends on the strength of the Vicsek-like interactions. Employing a subsystem-block-density distribution analysis, we determine the critical point and make an attempt to estimate the critical exponents. In contrast to the passive model, we find that the critical point is not located on the rectilinear diameter. A first estimate of the critical exponents $\beta$ and $\nu$ is consistent with the underlying 3d-Ising universality class observed for the passive model.