期刊
JOURNAL OF CHEMICAL PHYSICS
卷 133, 期 2, 页码 -出版社
AIP Publishing
DOI: 10.1063/1.3442412
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资金
- SFBRU-RFBR [phi28.2/037]
- European Community [RII3-CT2003-506350]
- European Research Council under the European Community [207916]
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. (C) 2010 American Institute of Physics. [doi:10.1063/1.3442412]
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