Dresden 2020 – scientific programme
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BP: Fachverband Biologische Physik
BP 41: Active Matter V (joint session DY/BP/CPP)
BP 41.1: Talk
Friday, March 20, 2020, 10:00–10:15, ZEU 160
A particle-field approach bridges phase separation and collective motion in active matter — •Robert Großmann1,2, Igor Aranson3, and Fernando Peruani2 — 1Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany — 2Laboratoire J.A. Dieudonné, Université Côte d’Azur, Nice, France — 3Department of Chemistry, Pennsylvania State University, University Park (PA), United States of America
Linking seemingly disconnected realms of active matter – active phase-separation of repulsive discs and collective motion of self-propelled rods – is a major contemporary challenge. We present a theoretical framework based on the representation of active particles by smoothed continuum fields which brings the simplicity of alignment-based models, enabling an analytical analysis, together with more realistic models for self-propelled objects including their steric, repulsive interactions. We demonstrate on the basis of the collision kinetics how nonequilibrium stresses acting among self-driven, anisotropic objects hinder the emergence of motility-induced phase separation and facilitate orientational ordering. Moreover, we report that impenetrable, anisotropic rods are found to form polar, moving clusters, whereas large-scale nematic structures emerge for soft rods, notably separated by a bistable coexistence regime. Thus, the symmetry of the ordered state is not dictated by the symmetry of the interaction potential but is rather a dynamical, emergent property of active systems. This theoretical framework can represent a variety of active systems: cell tissues, bacterial colonies, cytoskeletal extracts or shaken granular media.