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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Active Matter I (joint session DY/CPP/BP)

CPP 9.6: Talk

Monday, March 12, 2018, 11:30–11:45, BH-N 243

Localized States in an Active Phase-Field-Crystal Model — •Lukas Ophaus, Johannes Kirchner, Svetlana Gurevich, and Uwe Thiele — Institut für Theoretische Physik, WWU, Münster, Germany

The Phase-Field-Crystal (PFC) model provides a simple microscopic description of the thermodynamic transition from a fluid to a crystalline state [1]. The model can be combined with the Toner-Tu theory for self-propelled particles to obtain a model for crystallization (swarm formation) in active systems [2]. Within the resulting active PFC model, resting and traveling crystals can be identified. In the linear regime, we give analytical expressions for the transitions from the liquid state to both types of crystals. In addition, we provide a general semi-analytical criterion for the onset of motion in the nonlinear regime, that corresponds to a drift-pitchfork bifurcation. Like the passive PFC model [3], the active version describes a variety of localized states (LS) besides spatially extended crystals. In the spatially one-dimensional case we explore how the bifurcation structure (slanted homoclinic snaking) is amended by activity. Numerical continuation is applied to follow resting and traveling LS while varying the activity and mean concentration. A fold continuation allows us to determine the area of existence of different states in a two parameter plane. Finally, we look into the scattering behavior of LS through numerical time simulation. [1] M.J. Robbins et al., PRE 85, 061408 (2012). [2] A.M. Menzel and H. Löwen, PRL 110, 055702 (2013). [3] U. Thiele et al., PRE 87, 042915 (2013)