van der Meer B, Qi W, Sprakel J, Filion L, Dijkstra M
Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
Physical Chemistry and Soft Matter, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
Soft Matter. 2015 Dec 28;11(48):9385-92. doi: 10.1039/c5sm01520k.
In this paper we study a two-dimensional system of charged colloidal particles using Brownian dynamics simulations. We determine the phase diagram and investigate the dynamics of this system in the density regime where hexatic and solid phases are stable. We find that the dynamics in these phases is heterogeneous by means of the spontaneous formation and diffusion of highly mobile defects. We identify two key mechanisms associated with the areas of high mobility. The first mechanism involves the highly cooperative motion of a closed loop of particles which shift coherently along the loop until each particle has replaced the position of its predecessor in the chain. The second mechanism involves the spontaneous creation of vacancy-interstitial pairs which diffuse within the hexatic and solid phases. We further explore quantitatively the properties of the open-ended and closed rearrangement strings and find that in the crystal phase the string-size distribution can be approximately matched with a simple, random walk description of vacancies and interstitials on a lattice.
在本文中，我们使用布朗动力学模拟研究了二维带电胶体粒子系统。我们确定了相图，并研究了该系统在六方相和固相稳定的密度范围内的动力学。我们发现，通过高迁移率缺陷的自发形成和扩散，这些相中的动力学是不均匀的。我们确定了与高迁移率区域相关的两个关键机制。第一个机制涉及粒子闭环的高度协同运动，该闭环沿环连贯移动，直到每个粒子取代了其在链中前一个粒子的位置。第二个机制涉及空位-间隙对的自发产生，这些对在六方相和固相中扩散。我们进一步定量探索了开放式和封闭式重排串的性质，发现晶体相中串尺寸分布可以与晶格上空位和间隙的简单随机游走描述大致匹配。
