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Non-equilibrium phase separation with reactions: a canonical model and its behaviour
Journal of Statistical Mechanics: Theory and Experiment ( IF 2.4 ) Pub Date : 2020-05-28 , DOI: 10.1088/1742-5468/ab7e2d
Yuting I Li , Michael E Cates

Materials undergoing both phase separation and chemical reactions (defined here as all processes that change particle type or number) form an important class of non-equilibrium systems. Examples range from suspensions of self-propelled bacteria with birth-death dynamics, to bio-molecular condensates, or 'membraneless organelles', within cells. In contrast to their passive counterparts, such systems have conserved and non-conserved dynamics that do not, in general, derive from a shared free energy. This mismatch breaks time-reversal symmetry and leads to new types of dynamical competition that are absent in or near equilibrium. We construct a canonical scalar field theory to describe such systems, with conserved and non-conserved dynamics obeying Model B and Model A respectively (in the Hohenberg-Halperin classification), chosen such that the two free energies involved are incompatible. The resulting minimal model is shown to capture the various phenomenologies reported previously for more complicated models with the same physical ingredients, including microphase separation, limit cycles and droplet splitting. We find a low-dimensional subspace of parameters for which time-reversal symmetry is accidentally recovered, and show that here the dynamics of the order parameter field (but not its conserved current) is exactly the same as an equilibrium system in which microphase separation is caused by long-range attractive interactions.

中文翻译:

反应的非平衡相分离:典型模型及其行为

经历相分离和化学反应(这里定义为改变粒子类型或数量的所有过程)的材料形成了一类重要的非平衡系统。示例范围从具有生死动力学的自推进细菌的悬浮液,到细胞内的生物分子凝聚物或“无膜细胞器”。与其被动对应物相比,此类系统具有守恒和非守恒动力学,它们通常不源自共享的自由能。这种不匹配打破了时间反转对称性,并导致了在平衡中或接近平衡时不存在的新型动态竞争。我们构建了一个典型的标量场理论来描述这样的系统,其中守恒和非守恒动力学分别服从模型 B 和模型 A(在 Hohenberg-Halperin 分类中),选择使得所涉及的两个自由能不相容。所得的最小模型显示了之前报告的具有相同物理成分的更复杂模型的各种现象,包括微相分离、极限循环和液滴分裂。我们发现了一个低维的参数子空间,其时间反演对称性被意外恢复,并表明这里的有序参数场(但不是其守恒电流)的动力学与微相分离的平衡系统完全相同由长程吸引力相互作用引起。包括微相分离、极限循环和液滴分裂。我们发现了一个低维的参数子空间,其时间反转对称性被意外恢复,并表明这里的有序参数场(但不是其守恒电流)的动力学与微相分离为平衡系统的平衡系统完全相同由长程吸引力相互作用引起。包括微相分离、极限循环和液滴分裂。我们发现了一个低维的参数子空间,其时间反转对称性被意外恢复,并表明这里的有序参数场(但不是其守恒电流)的动力学与微相分离为平衡系统的平衡系统完全相同由长程吸引力相互作用引起。
更新日期:2020-05-28
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