Effective potential method for active particles

TL;DR

This paper explores the steady state behavior of active particles modeled with colored noise, revealing aggregation tendencies and discussing the applicability of effective potential approaches within an active matter framework.

Contribution

It introduces an effective potential method for active particles using the multidimensional unified colored noise approximation, bridging active matter and molecular fluid analysis.

Findings

Particles tend to aggregate due to colored noise and interactions.

Effective friction between particles is enhanced, promoting clustering.

The validity of the two-body potential approximation is critically discussed.

Abstract

We investigate the steady state properties of an active fluid modeled as an assembly of soft repulsive spheres subjected to Gaussian colored noise. Such a noise captures one of the salient aspects of active particles, namely the persistence of their motion and determines a variety of novel features with respect to familiar passive fluids. We show that within the so-called multidimensional unified colored noise approximation, recently introduced in the field of active matter, the model can be treated by methods similar to those employed in the study of standard molecular fluids. The system shows a tendency of the particles to aggregate even in the presence of purely repulsive forces because the combined action of colored noise and interactions enhances the the effective friction between nearby particles. We also discuss whether an effective two-body potential approach, which would allow to employ methods similar to those of density functional theory, is appropriate. The limits of such an approximation are discussed.