1. Coexistence of active Brownian disks: van der Waals theory and analytical results
- Author
-
Thomas Speck
- Subjects
Thermal equilibrium ,Physics ,Equation of state ,Statistical Mechanics (cond-mat.stat-mech) ,FOS: Physical sciences ,State (functional analysis) ,01 natural sciences ,010305 fluids & plasmas ,Surface tension ,symbols.namesake ,Temperature and pressure ,Classical mechanics ,Phase (matter) ,0103 physical sciences ,symbols ,van der Waals force ,010306 general physics ,Condensed Matter - Statistical Mechanics ,Brownian motion - Abstract
At thermal equilibrium, intensive quantities like temperature and pressure have to be uniform throughout the system, restricting inhomogeneous systems composed of different phases. The paradigmatic example is the coexistence of vapor and liquid, a state that can also be observed for active Brownian particles steadily driven away from equilibrium. Recently, a strategy has been proposed that allows to predict phase equilibria of active particles [Solon et al., Phys. Rev. E 97, 020602(R) (2018)2470-004510.1103/PhysRevE.97.020602]. Here we elaborate on this strategy and formulate it in the framework of a van der Waals theory for active disks. For a given equation of state, we derive the effective free energy analytically and show that it yields coexisting densities in very good agreement with numerical results. We discuss the interfacial tension and the relation to Cahn-Hilliard models.
- Published
- 2021
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