Coincidence of the freezing and the onset of caging in hard sphere and Lennard-Jones fluids

J Ruiz-Franco; E Zaccarelli; H J Schöpe; W van Megen

doi:10.1063/1.5114720

Coincidence of the freezing and the onset of caging in hard sphere and Lennard-Jones fluids

J Chem Phys. 2019 Sep 14;151(10):104501. doi: 10.1063/1.5114720.

Authors

J Ruiz-Franco¹, E Zaccarelli¹, H J Schöpe², W van Megen³

Affiliations

¹ CNR-ISC and Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 2, I-00185 Roma, Italy.
² Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
³ Department of Applied Physics, Royal Melbourne Institute of Technology, Melbourne, Victoria 3000, Australia.

PMID: 31521083
DOI: 10.1063/1.5114720

Abstract

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.