Phase separation of active Brownian particles in two dimensions: Anything for a quiet life

Abstract

Active Brownian particles display self-propelled movement, which can be modelled as arising from a one-body force. Although their interparticle interactions are purely repulsive, for strong self propulsion the swimmers phase separate into dilute and dense phases. We describe in detail a recent theory (Phys. Rev. E 100, 052604 (2019); Phys. Rev. Lett. 128, 26802 (2019)) for such motility induced phase-separation. Starting from the continuity equation and the force density balance, the description is based on four superadiabatic contributions to the internal force density. Here the superadiabatic forces are due to the flow in the system and they act on top of the adiabatic forces that arise from the equilibrium free energy. Phase coexistence is described by bulk state functions and agrees quantitatively with Brownian dynamics simulation results from the literature. We describe in detail all analytical steps to fully resolve the spatial and orientational dependence of the one-body density and current. The decomposition into angular Fourier series leads to coupling of total density, polarization and all higher modes. We describe the power functional approach, including the kinematic dependence of the superadiabatic force fields and the quiet life effect that pushes particles from fast to slow regions, and hence induces the phase separation.

arXiv comment18 pages

References in corpus (56)

• Motility-Induced Phase Separation
• Athermal Phase Separation of Self-Propelled Particles with no Alignment
• The 2019 Motile Active Matter Roadmap
• Emergent behavior in active colloids
• A continuum theory of phase separation kinetics for active Brownian particles
• Phase behaviour of active Brownian particles: The role of dimensionality
• Hydrodynamics determines collective motion and phase behavior of active colloids
• Pressure and Phase Equilibria in Interacting Active Brownian Spheres
• Full phase diagram of active Brownian disks: from melting to motility-induced phase separation
• Activity-induced phase separation and self-assembly in mixtures of active and passive particles
• Sedimentation, trapping, and rectification of dilute bacteria
• Microscopic theory for the phase separation of self-propelled repulsive disks
• Effective Interactions in Active Brownian Suspensions
• Effective Cahn-Hilliard equation for the phase separation of active Brownian particles
• Towards a 'Thermodynamics' of Active Matter
• Cooperative Motion of Active Brownian Spheres in Three-Dimensional Dense Suspensions
• Negative interfacial tension in phase-separated active suspensions
• Generalized thermodynamics of Motility-Induced Phase Separation: Phase equilibria, Laplace pressure, and change of ensembles
• Spatiotemporal order and emergent edge currents in active spinner materials
• Active colloidal suspensions: Clustering and phase behavior
• Virial pressure in systems of active Brownian particles
• Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles
• Active Particles Bound by Information Flows
• Motility-induced phase separation and coarsening in active matter
• Stochastic thermodynamics for active matter
• Critical behavior of active Brownian particles
• Power functional theory for Brownian dynamics
• Traveling fronts in active-passive particle mixtures
• Ideal bulk pressure of active Brownian particles
• Reentrance effect in the lane formation of driven colloids
• Chemical potential in active systems: predicting phase equilibrium from bulk equations of state?
• Mechanical pressure and momentum conservation in dry active matter
• Microscopic Origins of the Swim Pressure and the Anomalous Surface Tension of Active Matter
• Phase separation and multibody effects in three-dimensional active Brownian particles
• Topological protection of multiparticle dissipative transport
• Non-Equilibrium Surface Tension of the Vapour-Liquid Interface of Active Lennard-Jones Particles
• Active Brownian particles at interfaces: An effective equilibrium approach
• Non-negative Interfacial Tension in Phase-Separated Active Brownian Particles
• Phase coexistence of active Brownian particles
• Collective forces in scalar active matter
• Dynamical self-assembly of dipolar active Brownian particles in two dimensions
• Phase behaviour and dynamical features of a two-dimensional binary mixture of active/passive spherical particles
• Superadiabatic forces in Brownian many-body dynamics
• Nonequilibrium Ornstein-Zernike relation for Brownian many-body dynamics
• Local stress and pressure in an inhomogeneous system of spherical active Brownian particles
• Velocity gradient power functional for Brownian dynamics
• Coexistence of active Brownian discs: Van der Waals theory and analytical results
• Vapour-Liquid Coexistence of an Active Lennard-Jones fluid
• Nonequilibrium phase behaviour from minimization of free power dissipation
• Flow and structure in nonequilibrium Brownian many-body systems
• Structural nonequilibrium forces in driven colloidal systems
• Custom flow in overdamped Brownian Dynamics
• Active ideal sedimentation: Exact two-dimensional steady states
• Dynamic correlations in Brownian many-body systems
• Simultaneous polydirectional transport of colloidal bipeds
• Active interface polarization is a state function

Cited by in corpus (18)

• Power functional theory for many-body dynamics
• Flocking without alignment interactions in attractive active Brownian particles
• Mechanical Theory of Nonequilibrium Coexistence and Motility-Induced Phase Separation
• Active phase separation: new phenomenology from non-equilibrium physics
• Why Noether's Theorem applies to Statistical Mechanics
• Perspective: How to overcome dynamical density functional theory
• Force density functional theory in- and out-of-equilibrium
• Perspective: New directions in dynamical density functional theory
• Phase Coexistence in Nonreciprocal Quorum-Sensing Active Matter
• Kinetic temperature and pressure of an active Tonks gas
• Dynamic Decay and Superadiabatic Forces in the van Hove Dynamics of Bulk Hard Sphere Fluids
• Active crystallization from power functional theory
• Theory of Nonequilibrium Multicomponent Coexistence
• Reconsidering Power Functional Theory
• Dynamics and rupture of doped Motility Induced Phase Peparation
• Theory of Nonequilibrium Coexistence with Coupled Conserved and Nonconserved Order Parameters
• The geometric phase and the dry friction of sleeping tops on inclined planes
• Hydrodynamics of simple active liquids: the emergence of velocity correlations