Speck Thomas
Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany.
Phys Rev E. 2021 Jan;103(1-1):012607. doi: 10.1103/PhysRevE.103.012607.
At thermal equilibrium, intensive quantities like temperature and pressure have to be uniform throughout the system, restricting inhomogeneous systems composed of different phases. The paradigmatic example is the coexistence of vapor and liquid, a state that can also be observed for active Brownian particles steadily driven away from equilibrium. Recently, a strategy has been proposed that allows to predict phase equilibria of active particles [Solon et al., Phys. Rev. E 97, 020602(R) (2018)2470-004510.1103/PhysRevE.97.020602]. Here we elaborate on this strategy and formulate it in the framework of a van der Waals theory for active disks. For a given equation of state, we derive the effective free energy analytically and show that it yields coexisting densities in very good agreement with numerical results. We discuss the interfacial tension and the relation to Cahn-Hilliard models.
在热平衡状态下，诸如温度和压力等强度量在整个系统中必须是均匀的，这限制了由不同相组成的非均匀系统。典型的例子是蒸汽和液体的共存，这种状态也可以在稳定地远离平衡态的活性布朗粒子中观察到。最近，有人提出了一种策略，可以预测活性粒子的相平衡[索隆等人，《物理评论E》97，020602(R)(2018)2470 - 004510.1103/PhysRevE.97.020602]。在此，我们详细阐述这一策略，并在活性圆盘的范德瓦尔斯理论框架内对其进行表述。对于给定的状态方程，我们解析地推导有效自由能，并表明它得出的共存密度与数值结果非常吻合。我们讨论界面张力以及与相场Cahn - Hilliard模型的关系。
