Mechanical Theory of Nonequilibrium Coexistence and Motility-Induced Phase Separation

Abstract

Nonequilibrium phase transitions are routinely observed in both natural and synthetic systems. The ubiquity of these transitions highlights the conspicuous absence of a general theory of phase coexistence that is broadly applicable to both nonequilibrium and equilibrium systems. Here, we present a general mechanical theory for phase separation rooted in ideas explored nearly a half-century ago in the study of inhomogeneous fluids. The core idea is that the mechanical forces within the interface separating two coexisting phases uniquely determine coexistence criteria, regardless of whether a system is in equilibrium or not. We demonstrate the power and utility of this theory by applying it to active Brownian particles, predicting a quantitative phase diagram for motility-induced phase separation in both two and three dimensions. This formulation additionally allows for the prediction of novel interfacial phenomena, such as an increasing interface width while moving deeper into the two-phase region, a uniquely nonequilibrium effect confirmed by computer simulations. The self-consistent determination of bulk phase behavior and interfacial phenomena offered by this mechanical perspective provide a concrete path forward towards a general theory for nonequilibrium phase transitions.

References in corpus (11)

• Motility-Induced Phase Separation
• Pressure and Phase Equilibria in Interacting Active Brownian Spheres
• Towards a 'Thermodynamics' of Active Matter
• Nonreciprocity as a generic route to traveling states
• Flow phase diagrams for concentration-coupled shear banding
• Microscopic Origins of the Swim Pressure and the Anomalous Surface Tension of Active Matter
• Non-negative Interfacial Tension in Phase-Separated Active Brownian Particles
• Phase coexistence of active Brownian particles
• Phase separation of active Brownian particles in two dimensions: Anything for a quiet life
• Phase Coexistence Implications of Violating Newton's Third Law
• Mean-field theory for the structure of strongly interacting active liquids

Cited by in corpus (29)

• Non-reciprocity across scales in active mixtures
• Active phase separation: new phenomenology from non-equilibrium physics
• Theory of Capillary Tension and Interfacial Dynamics of Motility-Induced Phases
• Motility Induced Phase Separation and Frustration in Active Matter Swarmalators
• Nonequilibrium interfacial properties of chemically driven fluids
• Coexistence of uniform and oscillatory states resulting from nonreciprocity and conservation laws
• Phase Coexistence in Nonreciprocal Quorum-Sensing Active Matter
• Diffusion Transients in Motility-Induced Phase Separation
• Motility-induced clustering of active particles under soft confinement
• The Mechanics of Nucleation and Growth and the Surface Tensions of Active Matter
• Kinetic temperature and pressure of an active Tonks gas
• Non-equilibrium coexistence between a fluid and a hotter or colder crystal of granular hard disks
• Single-File Diffusion of Active Brownian Particles
• Time-dependent properties of run-and-tumble particles: Density relaxation
• Nematic Torques in Scalar Active Matter: when Fluctuations Favor Polar Order and Persistence
• Phase Separation, Capillarity, and Odd Surface Flows in Chiral Active Matter
• Theory of Nonequilibrium Multicomponent Coexistence
• Dynamical and structural properties of an absorbing phase transition: a case study from granular systems
• Active crystallization from power functional theory
• Self-organization of active colloids mediated by chemical interactions
• Theory for the Anomalous Phase Behavior of Inertial Active Brownian Particles
• Theory of Nonequilibrium Coexistence with Coupled Conserved and Nonconserved Order Parameters
• Mobility-induced phase separation in a binary mixture of active Brownian particles
• Steady inhomogeneous shear flows as mechanical phase transitions
• Bubble formation in active binary mixture model
• Chemotaxis-induced phase separation
• Theory of Nonequilibrium Crystallization and the Phase Diagram of Active Brownian Spheres
• Critical Motility-Induced Phase Separation in Three Dimensions is Consistent with Ising Universality
• Active Cahn-Hilliard theory for nonequilibrium phase separation: quantitative macroscopic predictions and a microscopic derivation