论文标题
示踪剂在连接到不同恒温器的软颗粒的致密混合物中扩散
Diffusion of a tracer in a dense mixture of soft particles connected to different thermostats
论文作者
论文摘要
我们研究示踪剂在连接到不同恒温器的颗粒的致密混合物中的动力学。从描述系统演化的过度抑制兰格文方程开始，我们得出了标记粒子在悬架中的自扩散系数的表达，在粒子之间的软相互作用的极限。我们的派生依赖于密度场遵守的Dean-Kawasaki方程的线性化以及示踪剂动力学的路径积分表示，扩展了与单个浴室接触的示踪剂保持的先前推导。我们的分析结果面临着布朗动力学模拟的结果。即使对于高密度，与数值模拟的一致性也非常好。我们展示了示踪剂的扩散率如何受到可能代表聚合物线圈的软颗粒的致富活性的影响，这可能与生物学介质中扩散率的测量结果相关。最后，我们的分析结果是一般的，可以应用于耦合到不同类型波动环境的示踪剂的扩散，只要它们的演变方程是线性的，并且示踪剂和浴缸之间的耦合较弱。
We study the dynamics of a tracer in a dense mixture of particles connected to different thermostats. Starting from the overdamped Langevin equations that describe the evolution of the system, we derive the expression of the self-diffusion coefficient of a tagged particle in the suspension, in the limit of soft interactions between the particles. Our derivation, which relies on the linearization of the Dean-Kawasaki equations obeyed by the density fields and on a path-integral representation of the dynamics of the tracer, extends previous derivations that held for tracers in contact with a single bath. Our analytical result is confronted to results from Brownian dynamics simulations. The agreement with numerical simulations is very good even for high densities. We show how the diffusivity of tracers can be affected by the activity of a dense environment of soft particles that may represent polymer coils -- a result that could be of relevance in the interpretation of measurements of diffusivity in biological media. Finally, our analytical result is general and can be applied to the diffusion of tracers coupled to different types of fluctuating environments, provided that their evolution equations are linear and that the coupling between the tracer and the bath is weak.
