Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, USA.
Division of Physical Chemistry, Lund University, 221 00 Lund, Sweden.
Phys Rev E. 2018 Feb;97(2-1):020602. doi: 10.1103/PhysRevE.97.020602.
Motility-induced phase separation (MIPS) arises generically in fluids of self-propelled particles when interactions lead to a kinetic slowdown at high densities. Starting from a continuum description of scalar active matter akin to a generalized Cahn-Hilliard equation, we give a general prescription for the mean densities of coexisting phases in flux-free steady states that amounts, at a hydrodynamics scale, to extremizing an effective free energy. We illustrate our approach on two well-known models: self-propelled particles interacting either through a density-dependent propulsion speed or via direct pairwise forces. Our theory accounts quantitatively for their phase diagrams, providing a unified description of MIPS.
当相互作用导致高密度时的动力学减速时，由自推进粒子组成的流体中会普遍出现由运动引起的相分离（MIPS）。从类似于广义 Cahn-Hilliard 方程的标量活性物质的连续描述出发，我们为通量自由稳定状态下共存相的平均密度提供了一个通用的规定，在流体力学尺度上，这相当于最大化有效自由能。我们在两个著名的模型上说明了我们的方法：自推进粒子通过密度相关的推进速度或通过直接的成对力相互作用。我们的理论对它们的相图进行了定量解释，为 MIPS 提供了统一的描述。
