Non-Equilibrium Surface Tension of the Vapour-Liquid Interface of Active Lennard-Jones Particles

Abstract

We study a three-dimensional system of self-propelled Brownian particles interacting via the Lennard-Jones potential. Using Brownian Dynamics simulations in an elongated simulation box, we investigate the steady states of vapour-liquid phase coexistence of active Lennard-Jones particles with planar interfaces. We measure the normal and tangential components of the pressure tensor along the direction perpendicular to the interface and verify mechanical equilibrium of the two coexisting phases. In addition, we determine the non-equilibrium interfacial tension by integrating the difference of the normal and tangential component of the pressure tensor, and show that the surface tension as a function of strength of particle attractions is well-fitted by simple power laws. Finally, we measure the interfacial stiffness using capillary wave theory and the equipartition theorem, and find a simple linear relation between surface tension and interfacial stiffness with a proportionality constant characterized by an effective temperature.

12 pages, 5 figures (Corrected typos and References)

References in corpus (8)

• Statistical Mechanics of Interacting Run-and-Tumble Bacteria
• When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
• Pressure and Phase Equilibria in Interacting Active Brownian Spheres
• Effective Interactions in Active Brownian Suspensions
• Towards a 'Thermodynamics' of Active Matter
• Why is surface tension a force parallel to the interface?
• Nonequilibrium equation of state in suspensions of active colloids
• Capillary waves at the liquid-vapor interface and the surface tension of water models

Cited by in corpus (4)

• 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