Hargus Cory, Epstein Jeffrey M, Mandadapu Kranthi K
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
Department of Physics, University of California, Berkeley, California 94720, USA.
Phys Rev Lett. 2021 Oct 22;127(17):178001. doi: 10.1103/PhysRevLett.127.178001.
Diffusive transport is characterized by a diffusivity tensor which may, in general, contain both a symmetric and an antisymmetric component. Although the latter is often neglected, we derive Green-Kubo relations showing it to be a general characteristic of random motion breaking time-reversal and parity symmetries, as encountered in chiral active matter. In analogy with the odd viscosity appearing in chiral active fluids, we term this component the odd diffusivity. We show how odd diffusivity emerges in a chiral random walk model, and demonstrate the applicability of the Green-Kubo relations through molecular dynamics simulations of a passive tracer particle diffusing in a chiral active bath.
扩散输运的特征是一个扩散张量，一般来说，它可能同时包含对称和反对称分量。尽管后者常常被忽略，但我们推导出格林 - 库博关系，表明它是手性活性物质中出现的打破时间反演和宇称对称性的随机运动的一个普遍特征。与手性活性流体中出现的奇黏滞性类似，我们将这个分量称为奇扩散率。我们展示了奇扩散率是如何在手性随机游走模型中出现的，并通过在一个手性活性浴中扩散的被动示踪粒子的分子动力学模拟，证明了格林 - 库博关系的适用性。
