Negative Interfacial Tension in Phase-Separated Active Brownian Particles

Julian Bialké, Jonathan T. Siebert, Hartmut Löwen, and Thomas Speck
Phys. Rev. Lett. 115, 098301 – Published 24 August 2015
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Abstract

We study numerically a model for active suspensions of self-propelled repulsive particles, for which a stable phase separation into a dilute and a dense phase is observed. We exploit the fact that for nonsquare boxes a stable “slab” configuration is reached, in which interfaces align with the shorter box edge. Evaluating a recent proposal for an intensive active swimming pressure, we demonstrate that the excess stress within the interface separating both phases is negative. The occurrence of a negative tension together with stable phase separation is a genuine nonequilibrium effect that is rationalized in terms of a positive stiffness, the estimate of which agrees excellently with the numerical data. Our results challenge effective thermodynamic descriptions and mappings of active Brownian particles onto passive pair potentials with attractions.

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  • Received 15 December 2014

DOI:https://doi.org/10.1103/PhysRevLett.115.098301

© 2015 American Physical Society

Authors & Affiliations

Julian Bialké1, Jonathan T. Siebert2, Hartmut Löwen1, and Thomas Speck2

  • 1Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
  • 2Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany

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Issue

Vol. 115, Iss. 9 — 28 August 2015

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