Pressure and Phase Equilibria in Interacting Active Brownian Spheres

Alexandre P. Solon*, Joakim Stenhammar, Raphael Wittkowski, Mehran Kardar, Yariv Kafri, Michael E. Cates, Julien Tailleur

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We derive a microscopic expression for the mechanical pressure P in a system of spherical active Brownian particles at density ρ. Our exact result relates P, defined as the force per unit area on a bounding wall, to bulk correlation functions evaluated far away from the wall. It shows that (i) P(ρ) is a state function, independent of the particle-wall interaction; (ii) interactions contribute two terms to P, one encoding the slow-down that drives motility-induced phase separation, and the other a direct contribution well known for passive systems; and (iii) P is equal in coexisting phases. We discuss the consequences of these results for the motility-induced phase separation of active Brownian particles and show that the densities at coexistence do not satisfy a Maxwell construction on P.

Original languageEnglish
Article number198301
Pages (from-to)1-6
Number of pages6
JournalPhysical Review Letters
Volume114
Issue number19
Early online date11 May 2015
DOIs
Publication statusPublished - 15 May 2015

Keywords

  • SEPARATION
  • PARTICLES
  • MOTION
  • HYDRODYNAMICS
  • MOTILITY
  • BEHAVIOR
  • COLLOIDS

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