Effective interactions in active Brownian particles

TL;DR

This paper introduces an inverse method to derive effective pair potentials for active Brownian particles, accurately capturing their structure and enabling the measurement of effective thermodynamic quantities despite their nonequilibrium nature.

Contribution

The study applies an inverse method to active particles, revealing effective potentials that describe their structure and thermodynamics, extending previous equilibrium-based approaches.

Findings

Effective potentials accurately describe active particle structure.

Active motion influences the form of effective interactions.

Thermodynamic quantities like pressure can be inferred from these potentials.

Abstract

We report an approach to obtain effective pair potentials which describe the structure of two-dimensional systems of active Brownian particles. The pair potential is found by an inverse method, which matches the radial distribution function found from two different schemes. The inverse method, previously demonstrated via simulated equilibrium configurations of passive particles, has now been applied to a suspension of active particles. Interestingly, although active particles are inherently not in equilibrium, we still obtain effective interaction potentials which accurately describe the structure of the active system. Treating these effective potentials as if they were those of equilibrium systems, furthermore allows us to measure effective chemical potentials and pressures. Both the passive interactions and active motion of the active Brownian particles contribute to their effective interaction potentials.