Nonequilibrium phase behaviour from minimization of free power dissipation

TL;DR

This paper introduces a general theoretical framework based on power functional theory to describe phase coexistence in nonequilibrium Brownian systems, successfully applied to active soft sphere swimmers.

Contribution

It develops a novel theory for nonequilibrium phase behavior using free power dissipation minimization, validated through simulations and analytical approximations.

Findings

The theory accurately predicts motility-induced phase separation.

Simulation results align well with the theoretical predictions.

Dissipated free power is a key quantity in describing phase coexistence.

Abstract

We develop a general theory for describing phase coexistence between nonequilibrium steady states in Brownian systems, based on power functional theory (M. Schmidt and J.M. Brader, J. Chem. Phys. 138, 214101 (2013)). We apply the framework to the special case of fluid-fluid phase separation of active soft sphere swimmers. The central object of the theory, the dissipated free power, is calculated via computer simulations and compared to a simple analytical approximation. The theory describes well the simulation data and predicts motility-induced phase separation due to avoidance of dissipative clusters.