CNR-ISC and Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 2, I-00185 Roma, Italy.
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
J Chem Phys. 2019 Sep 14;151(10):104501. doi: 10.1063/1.5114720.
In this article, we examine the collective particle dynamics, as expressed by the time correlation function of the longitudinal particle current density, of several different fluids in the vicinity of their freezing points/lines. We consider and compare results obtained by dynamic light scattering for a suspension of hard spheres and by molecular dynamics for fluids with hard sphere and Lennard-Jones interactions. The latter are performed along both an isotherm and an isochore. In all cases, we find a qualitative change in the collective dynamics, within the resolution of the data, when their respective freezing lines are crossed. We associate this change with the onset of caging. The new results for the Lennard-Jones fluid reported here confirm that the occurrence of caging, found previously for systems of hard spheres, is a more general feature that distinguishes a metastable fluid from one in thermodynamic equilibrium.
在本文中，我们研究了几种不同流体在接近其冰点/线时的集体粒子动力学，表现为纵向粒子电流密度的时间相关函数。我们考虑并比较了通过动态光散射对硬球悬浮液获得的结果以及通过分子动力学对具有硬球和 Lennard-Jones 相互作用的流体获得的结果。后者沿着等温和等容两种情况进行。在所有情况下，当各自的冻结线被穿过时，我们发现了集体动力学在数据分辨率内的定性变化。我们将这种变化与笼效应的出现联系起来。这里报告的新的 Lennard-Jones 流体结果证实，先前在硬球系统中发现的笼效应是一种更普遍的特征，它将亚稳流体与处于热力学平衡的流体区分开来。
