论文标题
驱动二进制胶体中动态异质性的长度尺度
Length-scales of Dynamic Heterogeneity in a Driven Binary Colloid
论文作者
论文摘要
在这里，我们研究了由布朗动力学模拟的均匀电场的对称性胶体的水悬浮液中的特征长度尺度。我们考虑了一个足够强大的电场，其中类似系统中的类似电荷形成了宏观泳道。我们构建了表征结构阶的空间相关函数和在给定时间内横向到电场的不同迁移率的粒子的空间相关函数。我们将这些函数称为相等的时间密度相关函数（ETDCF）。不同电荷粒子之间的ETDCF（无论迁移率如何）称为结构ETDCF，而不同迁移率的颗粒之间的ETDCF称为动态ETDCF。我们通过将ETDCF的信封拟合到指数依赖性来提取相关的特征长度。我们发现，慢粒子的结构ETDCF和动力学ETDCF会随着时间而增加。这表明慢速颗粒在快速颗粒的背景下经历了微相分离，这些粒子驱动平面横向到车道的结构模式。可以通过视频微观镜进行粒子运动后直接针对胶体系统测量ETDCF，并且可能有助于从平衡中理解模式。
Here we study characteristic length scales in an aqueous suspension of symmetric oppositely charged colloid subject to a uniform electric field by Brownian Dynamics simulations. We consider a sufficiently strong electric field where the like charges in the system form macroscopic lanes. We construct spatial correlation functions characterizing structural order and that of particles of different mobilities in-plane transverse to the electric field at a given time. We call these functions as equal time density correlation function (ETDCF). The ETDCF between particles of different charges, irrespective of mobilities, are called structural ETDCFs, while those between particles of different mobilities are called the dynamic ETDCF. We extract the characteristic length of correlation by fitting the envelopes of the ETDCFs to exponential dependence. We find that structural ETDCF and the dynamical-ETDCFs of the slow particles increase with time. This suggests that the slow particles undergo microphase separation in the background of the fast particles which drive the structural pattern in the plane transverse to the lanes. The ETDCFs can be measured for colloidal systems directly following particle motion by video-microscopy and may be useful to understand patterns out of equilibrium.
