Li Yan-Wei, Zhu You-Liang, Sun Zhao-Yan
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China and Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters, College of Physical Science and Technology, Yili Normal University, Yining 835000, China.
Phys Rev E. 2016 Dec;94(6-1):062601. doi: 10.1103/PhysRevE.94.062601. Epub 2016 Dec 1.
We numerically investigate the connection between spatial density correlation and dynamical heterogeneity in glass-forming liquids. We demonstrate that the cluster size defined by the spatial aggregation of densely packed particles (DPPs) can better capture the difference between the dynamics of the Lennard-Jones glass model and the Weeks-Chandler-Andersen truncation model than the commonly used pair correlation functions. More interestingly, we compare the mobility of DPPs and loosely packed particles, and we find that high local density correlates well with slow dynamics in systems with relatively hard repulsive interactions but links to mobile ones in the system with soft repulsive interactions at one relaxation time scale. Our results show clear evidence that the above model dependence behavior stems from the hopping motion of DPPs at the end of the caging stage due to the compressive nature of soft repulsive spheres, which activates the dynamics of DPPs in the α relaxation stage.
我们通过数值方法研究了玻璃形成液体中空间密度关联与动力学非均匀性之间的联系。我们证明，由紧密堆积粒子（DPPs）的空间聚集定义的团簇大小，比常用的对关联函数能更好地捕捉 Lennard-Jones 玻璃模型和 Weeks-Chandler-Andersen 截断模型动力学之间的差异。更有趣的是，我们比较了 DPPs 和松散堆积粒子的迁移率，发现在一个弛豫时间尺度上，在具有相对较强排斥相互作用的系统中，高局部密度与缓慢动力学密切相关，而在具有软排斥相互作用的系统中则与可移动的动力学相关。我们的结果清楚地表明，上述模型依赖行为源于软排斥球的压缩性质导致的 DPPs 在笼蔽阶段末期的跳跃运动，这激活了 α 弛豫阶段 DPPs 的动力学。
