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Collective modes in simple melts: Transition from soft spheres to the hard sphere limit

Khrapak, Sergey and Klumov, Boris and Couedel, L. (2017) Collective modes in simple melts: Transition from soft spheres to the hard sphere limit. Scientific Reports, 7, p. 7985. Nature Publishing Group. DOI: 10.1038/s41598-017-08429-5 ISSN 2045-2322

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Abstract

We study collective modes in a classical system of particles with repulsive inverse-power-law (IPL) interactions in the fluid phase, near the fluid-solid coexistence (IPL melts). The IPL exponent is varied from n = 10 to n = 100 to mimic the transition from moderately soft to hard-sphere-like interactions. We compare the longitudinal dispersion relations obtained using molecular dynamic (MD) simulations with those calculated using the quasi-crystalline approximation (QCA) and find that this simple theoretical approach becomes grossly inaccurate for n >  20. Similarly, conventional expressions for high-frequency (instantaneous) elastic moduli, predicting their divergence as n increases, are meaningless in this regime. Relations of the longitudinal and transverse elastic velocities of the QCA model to the adiabatic sound velocity, measured in MD simulations, are discussed for the regime where QCA is applicable. Two potentially useful freezing indicators for classical particle systems with steep repulsive interactions are discussed.

Item URL in elib:https://elib.dlr.de/114468/
Document Type:Article
Title:Collective modes in simple melts: Transition from soft spheres to the hard sphere limit
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Khrapak, Sergeydlr, sergey.khrapak (at) dlr.deUNSPECIFIED
Klumov, Borisaix-marseille-universityUNSPECIFIED
Couedel, L.cnrs, aix-marseille universiteUNSPECIFIED
Date:11 August 2017
Journal or Publication Title:Scientific Reports
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:7
DOI :10.1038/s41598-017-08429-5
Page Range:p. 7985
Publisher:Nature Publishing Group
ISSN:2045-2322
Status:Published
Keywords:collective modes in fluids, melts, acoustic waves in fluids, collective motion in simple fluids
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Komplexe Plasmen / Theory, Simulation
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Materials Physics in Space > Research Group Complex Plasma
Institute of Materials Physics in Space
Deposited By: Khrapak, Sergey
Deposited On:04 Oct 2017 10:01
Last Modified:08 Mar 2018 18:36

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