Department of Physics and Soft Matter Program, Syracuse University, Syracuse, New York 13244, USA.
Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), 50009 Zaragoza, Spain.
Phys Rev E. 2017 Jan;95(1-1):012601. doi: 10.1103/PhysRevE.95.012601. Epub 2017 Jan 5.
Active Brownian particles (ABPs) represent a minimal model of active matter consisting of self-propelled spheres with purely repulsive interactions and rotational noise. Here we examine the pressure of ABPs in two dimensions in both closed boxes and systems with periodic boundary conditions and show that its nonmonotonic behavior with density is a general property of ABPs and is not the result of finite-size effects. We correlate the time evolution of the mean pressure towards its steady-state value with the kinetics of motility-induced phase separation. For parameter values corresponding to phase-separated steady states, we identify two dynamical regimes. The pressure grows monotonically in time during the initial regime of rapid cluster formation, overshooting its steady-state value and then quickly relaxing to it, and remains constant during the subsequent slower period of cluster coalescence and coarsening. The overshoot is a distinctive feature of active systems.
活性布朗粒子（ABPs）是一种主动物质的最小模型，由具有纯排斥相互作用和旋转噪声的自推进球体组成。在这里，我们在二维空间中研究了封闭盒和周期性边界条件系统中 ABPs 的压力，并表明其与密度的非单调行为是 ABPs 的普遍性质，而不是有限尺寸效应的结果。我们将平均压力向稳态值的时间演化与运动诱导相分离的动力学相关联。对于对应于相分离稳态的参数值，我们确定了两个动力学区域。在快速聚团形成的初始阶段，压力随时间单调增长，超过其稳态值，然后迅速恢复到稳态值，并且在随后的聚团合并和粗化的较慢阶段保持不变。过冲是主动系统的一个独特特征。
