SKM 2021 – scientific programme
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BP: Fachverband Biologische Physik
BP 1: Statistical physics of biological systems (joint session BP/DY)
BP 1.2: Talk
Monday, September 27, 2021, 10:30–10:45, H1
Collisions increase self-diffusion in odd-diffusive systems — •Erik Kalz1,2, Iman Abdoli1, Hidde Derk Vuijk1, Jens-Uwe Sommer1,2, and Abhinav Sharma1,2 — 1Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden — 2Technische Universität Dresden, Institut für Theoretische Physik 01069 Dresden
It is generally believed that collisions of particles reduce the self-diffusion coefficient. We show that in odd-diffusive systems, which are characterized by diffusion tensors with anti-symmetric elements, collisions surprisingly can enhance the self-diffusion. In these systems, due to an inherent curving effect, the motion of particles is facilitated, instead of hindered by collisions. We refer to this as an overdamped swing-by effect. Consistent with this we find that the collective diffusion remains unaffected. We demonstrate this counterintuitive behavior in a system of Brownian particles under Lorentz force. Using a geometric model, we theoretically predict a magnetic-field governed crossover from a reduced to an enhanced self-diffusion. The physical interpretation is quantitatively supported by the force-autocorrelation function, which turns negative with increasing magnetic field. Using Brownian dynamic simulations, we show that the predictions are also valid for active chiral particles as another odd-diffusive system.