发表机构
Universidad de Almería; Heinrich-Heine-Universität Düsseldorf; German Aerospace Center (DLR)（阿尔梅里亚大学; 杜塞尔多夫海因里希·海涅大学; 德国航空航天中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究采用被动微流变学结合朗之万动力学模拟与模式耦合理论，分析近玻璃转变密度硬胶体系统的动力学异质性，揭示示踪粒子动力学的耦合转变规律及迁移率区域的密度依赖特性。
AI 中文摘要
动力学异质性是过冷液体的标志之一，其性质及相关性已通过理论、模拟和实验展开研究。本工作中，我们提出通过示踪粒子的动力学（被动微流变学）监测方法，分析接近玻璃转变密度的硬胶体系统中的动力学异质性，采用朗之万动力学模拟和模式耦合理论开展研究。我们对动力学异质性研究中的不同可观测指标进行适配，使其可从单个示踪粒子的轨迹计算得到。示踪粒子的动力学呈现出转变：当示踪粒子尺寸较小时，其与环境（bath）解耦程度最高；当示踪粒子尺寸较大时，则进入强耦合区域。理论和模拟均表明，示踪粒子的非高斯参数在两种区域的交叉尺寸处达到最大值，且高度依赖于环境密度。我们还研究了动态 susceptibility，但该参数对示踪粒子尺寸或环境密度的依赖程度较小。最后，我们利用微流变学研究了不同迁移率区域的存在性：尽管示踪粒子轨迹确实显示出迁移率升高的阶段，但估算的区域尺寸随环境密度增大而减小，这与体相（bulk）的聚类分析结果相反。
英文摘要
Dynamical heterogeneities are one of the hallmarks of supercooled liquids, and their properties and relevance have been studied with theory, simulations and experiments. In this work, we propose to monitor the dynamics of tracer particles (passive microrheology) to analyze the dynamical heterogeneities in a system of hard colloids close to the glass transition density, using Langevin dynamics simulations and mode coupling theory. Different observables, typical in the study of the dynamical heterogeneities are adapted to be calculated from the trajectory of a single tracer particle. The tracer dynamics shows a transition from a regime where it is most decoupled from the bath for small tracer size to a strong coupling regime for large tracers. Both theory and simulations show that the non-Gaussian parameter of the tracer is maximal for tracer sizes at the crossover between both regimes, and is highly dependent on the bath density. The dynamic susceptibility is also studied, but this parameter shows a minor dependence on both the tracer size or the bath density. Finally, the existence of regions with different mobility is also studied with microrheology. Although the tracer trajectory indeed shows stages with increased mobility, the estimated size of the regions decreases with the bath density, contrary to the results from cluster analysis in the bulk.
