Onset of collective excitations in the transverse dynamics of simple fluids

Autor(en)

Eleonora Guarini, Martin Neumann, Alessio De Francesco, Ferdinando Formisano, Alessandro Cunsolo, Wouter Montfrooij, Daniele Colognesi, Ubaldo Bafile

Abstrakt

A thorough analysis of the transverse current autocorrelation function obtained by molecular dynamics simulations of a dense Lennard-Jones fluid reveals that even such a simple system is characterized by a varied dynamical behavior with changing length scale. By using the exponential expansion theory, we provide a full account of the time correlation at wavevectors Q between the upper boundary of the hydrodynamic region and Q_p/2, with Q_p being the position of the main peak of the static structure factor. In the Q range studied, we identify and accurately locate the wavevector at which shear wave propagation starts to take place, and show clearly how this phenomenon may be represented by a damped harmonic oscillator changing, in a continuous way, from an overdamped to an underdamped condition. The decomposition into exponential modes allows one to convincingly establish not only the crossover related to the onset of transverse waves but, surprisingly, also the existence of a second pair of modes equivalent to another oscillator that undergoes, at higher Q values, a similarly smooth over to underdamped transition.

Organisation(en)

Computergestützte Physik und Physik der Weichen Materie

Externe Organisation(en)

Università degli Studi di Firenze, Institut Laue-Langevin (ILL), University of Wisconsin, Madison, University of Missouri-Columbia, Consiglio Nazionale delle Ricerche

Journal

Physical Review E

Band

107

Anzahl der Seiten

8

ISSN

2470-0045

DOI

https://doi.org/10.1103/PhysRevE.107.014139

Publikationsdatum

01-2023

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 103043 Computational Physics, 103029 Statistische Physik

Schlagwörter

ASJC Scopus Sachgebiete

Condensed Matter Physics, Statistical and Nonlinear Physics, Statistics and Probability

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/9636c02d-35f9-4331-9a62-9c6653deca82