Růžička Štěpán, Allen Michael P
Laboratoire de Physique des Solides, Université Paris-Sud & CNRS, UMR 8502, 91405, Orsay, France.
Department of Physics, University of Warwick, CV4 7AL, Coventry, UK.
Eur Phys J E Soft Matter. 2015 Jun;38(6):68. doi: 10.1140/epje/i2015-15068-5. Epub 2015 Jun 30.
Supercooled colloidal or molecular systems at low densities are known to form liquid, crystalline or glassy drops, which may remain isolated for a long time before they aggregate. This paper analyses the properties of this large time window, and how it can be tackled by computer simulation. We use single-particle and virtual move Monte Carlo simulations of short-range attractive spheres which are undercooled to the temperature region, where the spinodal intersects the attractive glass line. We study two different systems and we report the following kinetic behavior. A low-density system is shown to exhibit universal linear growth regimes under single-particle Monte Carlo correlating the growth rate to the local structure. These regimes are suppressed under collective motion, where droplets aggregate into a single large disordered domain. It is shown that the aggregation can be avoided and linear regimes recovered, if long-range repulsion is added to the short-range attraction. The results provide an insight into the behavior of the virtual move algorithm generating cluster moves according to the local forcefields. We show that different choices of maximum Monte Carlo displacement affect the dynamical trajectories but lead to the same kinetically slowed down or arrested states.
已知低密度的过冷胶体或分子系统会形成液体、晶体或玻璃状液滴，这些液滴在聚集之前可能会长时间保持孤立状态。本文分析了这个大时间窗口的特性，以及如何通过计算机模拟来处理它。我们使用短程吸引球体的单粒子和虚拟移动蒙特卡罗模拟，将其过冷到旋节线与吸引玻璃线相交的温度区域。我们研究了两种不同的系统，并报告了以下动力学行为。一个低密度系统在单粒子蒙特卡罗模拟下表现出普遍的线性生长模式，将生长速率与局部结构相关联。在集体运动下，这些模式会受到抑制，此时液滴聚集成一个单一的大无序域。结果表明，如果在短程吸引中加入长程排斥力，就可以避免聚集并恢复线性模式。这些结果为根据局部力场生成簇移动的虚拟移动算法的行为提供了见解。我们表明，最大蒙特卡罗位移的不同选择会影响动力学轨迹，但会导致相同的动力学减速或停滞状态。
