van Damme Robin, Rodenburg Jeroen, van Roij René, Dijkstra Marjolein
Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands.
Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
J Chem Phys. 2019 Apr 28;150(16):164501. doi: 10.1063/1.5086733.
To study the role of torque in motility-induced phase separation (MIPS), we simulate a system of self-propelled particles whose shape varies smoothly from isotropic (disks/spheres) to weakly elongated (rods). We construct the phase diagrams of 2D active disks, 3D active spheres, and 2D/3D active rods of aspect ratio l/σ = 2. A stability analysis of the homogeneous isotropic phase allows us to predict the onset of MIPS based on the effective swimming speed and rotational diffusion of the particles. Both methods find suppression of MIPS as the particle shape is elongated. We propose a suppression mechanism based on the duration of collisions and argue that this mechanism can explain both the suppression of MIPS found here for rodlike particles and the enhancement of MIPS found for particles with Vicsek interactions.
为了研究扭矩在运动诱导相分离（MIPS）中的作用，我们模拟了一个自驱动粒子系统，其形状从各向同性（圆盘/球体）平滑变化到弱伸长（棒状）。我们构建了纵横比l/σ = 2的二维活性圆盘、三维活性球体和二维/三维活性棒的相图。对均匀各向同性相的稳定性分析使我们能够基于粒子的有效游动速度和旋转扩散来预测MIPS的起始。两种方法都发现随着粒子形状伸长，MIPS受到抑制。我们提出了一种基于碰撞持续时间的抑制机制，并认为该机制可以解释此处发现的棒状粒子对MIPS的抑制以及具有Vicsek相互作用的粒子对MIPS的增强。
