Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 54: Active Matter II (joint session DY/BP/CPP, organized by DY)

CPP 54.11: Talk

Thursday, March 23, 2017, 12:30–12:45, HÜL 186

Active crystals on the sphere — •Simon Praetorius¹, Axel Voigt¹, Raphael Wittkowski², and Hartmut Löwen³ — ¹Institute of Scientific Computing, Technische Universität Dresden, D-01062 Dresden, Germany — ²Institut für Theoretische Physik Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany — ³Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany

Two-dimensional crystals on curved manifolds like a sphere exhibit nontrivial defect structures. Here we consider "active" crystals on the sphere which are composed of self-propelled particles. A coarse-grained model is proposed by unifying the Phase-Field Crystal approach with a Toner-Tu-like theory which involves a density and a polarization field on the sphere. Depending on the strength of the self-propulsion, four different dynamical modes are found: a resting crystal, a self-spinning "vortex-vortex" crystal containing two vortical poles with integer defects of the polarization, a "source-sink" crystal and a travelling/spinning lamellar. We analyze the dependence of orientational and translational defects on the activity of the crystal.