Dynamical heterogeneities and defects in two-dimensional soft colloidal crystals.
Dynamical heterogeneities and defects in two-dimensional soft colloidal crystals.
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DOI：
10.1039/c5sm01520k
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发表时间：
2015-12
期刊：
影响因子：
3.4
通讯作者：
B. van der Meer;W. Qi;J. Sprakel;L. Filion;M. Dijkstra
中科院分区：
文献类型：
--
作者：
B. van der Meer;W. Qi;J. Sprakel;L. Filion;M. Dijkstra
本文用布朗动力学模拟方法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相和固相稳定的密度状态下的动力学。通过高流动性缺陷的自发形成和扩散，我们发现这些相中的动力学是不均匀的。我们确定了与高流动性区域相关的两个关键机制。第一种机制涉及粒子闭环的高度协同运动，这些粒子沿着环一致移动，直到每个粒子取代其在链中的前身的位置。第二种机制涉及在六相和固相中扩散的空位-间隙对的自发产生。我们进一步定量地探讨了开放和封闭重排弦的性质，并发现在晶体相中，弦的大小分布可以近似地与晶格上空位和间隙的简单随机游动描述相匹配。
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.