Strefler Jessica, Erdmann Udo, Schimansky-Geier Lutz
Institut für Physik, Humboldt-Universität Berlin, Newtonstrasse 15, 12489 Berlin, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Sep;78(3 Pt 1):031927. doi: 10.1103/PhysRevE.78.031927. Epub 2008 Sep 30.
We consider a three-dimensional model of active Brownian particles interacting via a Morse-type potential. The system exhibits two modes of motion: translation and a coherent rotation in a torus-shape structure. We observe noise-induced transitions in both directions between the two states. These occur at different noise intensities, thus leading to a hysteresis curve. For certain parameter regions, the system switches persistently between the states such that the center of mass alternates between ballistic and diffusive motion. The coherent rotation leads to a pronounced mean angular momentum that changes its direction diffusively. We derive an analytic expression for the diffusion of the angular momentum of one particle in an external harmonic potential and show that it is always faster than the stochastic switching of the direction of motion in the two-dimensional case.
我们考虑了一个通过莫尔斯型势相互作用的活性布朗粒子的三维模型。该系统呈现出两种运动模式：平移以及在环面形状结构中的相干旋转。我们观察到在两种状态之间双向的噪声诱导转变。这些转变发生在不同的噪声强度下，从而导致一条滞后曲线。对于某些参数区域，系统在两种状态之间持续切换，使得质心在弹道运动和扩散运动之间交替。相干旋转导致了一个显著的平均角动量，其方向以扩散方式变化。我们推导了一个在外部谐波势中单个粒子角动量扩散的解析表达式，并表明在二维情况下，它总是比运动方向的随机切换更快。
