Collective excitations in supercritical fluids: analytical and molecular dynamics study of "positive" and "negative" dispersion.

The Journal of Chemical Physics
Taras BrykMario Santoro

Abstract

The approach of generalized collective modes is applied to the study of dispersion curves of collective excitations along isothermal lines of supercritical pure Lennard-Jones fluid. An effect of structural relaxation and other nonhydrodynamic relaxation processes on the dispersion law is discussed. A simple analytical expression for the dispersion law in the long-wavelength region of acoustic excitations is obtained within a three-variable viscoelastic model of generalized hydrodynamics. It is shown that the deviation from the linear dependence in the long-wavelength region can be either "positive" or "negative" depending on the ratio between the high-frequency (elastic) and isothermal speed of sound. An effect of thermal fluctuations on positive and negative dispersion is estimated from the analytical solution of a five-variable thermoviscoelastic model that generalizes the results of the viscoelastic treatment. Numerical results are reported for a Lennard-Jones supercritical fluid along two isothermal lines T(*)=1.71,4.78 with different densities and discussed along the theoretical expressions derived.

References

Jul 1, 1988·Physical Review A: General Physics· de Schepper IM de Graaf LA
Jun 21, 2001·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·T Bryk, I Mryglod
Mar 23, 2002·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·T ScopignoF Sette
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Oct 10, 2006·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Song-Ho Chong

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Citations

Oct 28, 2011·The Journal of Chemical Physics·Taras Bryk, J-F Wax
Jan 25, 2013·The Journal of Chemical Physics·Taras BrykTullio Scopigno
Dec 20, 2012·The Journal of Chemical Physics·Taras Bryk, Ivan Klevets
Feb 13, 2015·Proceedings of the National Academy of Sciences of the United States of America·Eva Arianna Aurelia PognaTullio Scopigno
Feb 6, 2013·Scientific Reports·F A GorelliT Scopigno
Jan 22, 2018·The Journal of Chemical Physics·J S HansenJeppe C Dyre
Jul 19, 2013·Journal of Physics. Condensed Matter : an Institute of Physics Journal·J-F Wax, Taras Bryk
Aug 2, 2012·Journal of Physics. Condensed Matter : an Institute of Physics Journal·Alessandro Cunsolo
Apr 15, 2015·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Taras Bryk
Dec 7, 2018·The Journal of Chemical Physics·Ayumi Takemoto, Kenichi Kinugawa
Nov 2, 2012·Journal of Physics. Condensed Matter : an Institute of Physics Journal·Taras Bryk, J-F Wax
Sep 8, 2016·Journal of Physics. Condensed Matter : an Institute of Physics Journal·Yu D FominK Trachenko
Oct 28, 2014·Journal of Physics. Condensed Matter : an Institute of Physics Journal·Beatriz G del Rio, Luis E González
Sep 10, 2018·The Journal of Chemical Physics·Beatriz G Del RioEmily A Carter
May 10, 2020·The Journal of Chemical Physics·D Duque-ZumajoPep Español
Apr 4, 2014·Journal of Physics. Condensed Matter : an Institute of Physics Journal·J-F Wax, Taras Bryk
Aug 16, 2017·The Journal of Chemical Physics·Taras BrykA D Trokhymchuk
May 17, 2012·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·V V BrazhkinK Trachenko
Sep 3, 2013·Physical Review Letters·Taras BrykAri P Seitsonen
Nov 7, 2014·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Taras BrykTullio Scopigno
May 5, 2018·The Journal of Physical Chemistry. B·T BrykT Scopigno
Sep 26, 2017·The Journal of Physical Chemistry Letters·T BrykT Scopigno

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Methods Mentioned

BETA
X-ray
inelastic neutron scattering

Software Mentioned

GCM
MCT
MD

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