dorsal/arxiv
View SchemaSite-site memory equation approach in study of density/pressure dependence of translational diffusion coefficient and rotational relaxation time of polar molecular solutions: acetonitrile in water, methanol in water, and methanol in acetonitrile
| Authors | A. E. Kobryn, T. Yamaguchi, F. Hirata |
|---|---|
| Categories | |
| ArXiv ID | physics/0502128 |
| URL | https://arxiv.org/abs/physics/0502128 |
| DOI | 10.1063/1.1884998 |
| Journal | J. Chem. Phys. 122 (2005) 184511 |
Abstract
We present results of theoretical study and numerical calculation of the dynamics of molecular liquids based on combination of the memory equation formalism and the reference interaction site model - RISM. Memory equations for the site-site intermediate scattering functions are studied in the mode-coupling approximation for the first order memory kernels, while equilibrium properties such as site-site static structure factors are deduced from RISM. The results include the temperature-density(pressure) dependence of translational diffusion coefficients D and orientational relaxation times t for acetonitrile in water, methanol in water and methanol in acetonitrile, all in the limit of infinite dilution. Calculations are performed over the range of temperatures and densities employing the SPC/E model for water and optimized site-site potentials for acetonitrile and methanol. The theory is able to reproduce qualitatively all main features of temperature and density dependences of D and t observed in real and computer experiments. In particular, anomalous behavior, i.e. the increase in mobility with density, is observed for D and t of methanol in water, while acetonitrile in water and methanol in acetonitrile do not show deviations from the ordinary behavior. The variety exhibited by the different solute-solvent systems in the density dependence of the mobility is interpreted in terms of the two competing origins of friction, which interplay with each other as density increases: the collisional and dielectric frictions which, respectively, increase and decrease with increasing density.
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"abstract": "We present results of theoretical study and numerical calculation of the\ndynamics of molecular liquids based on combination of the memory equation\nformalism and the reference interaction site model - RISM. Memory equations for\nthe site-site intermediate scattering functions are studied in the\nmode-coupling approximation for the first order memory kernels, while\nequilibrium properties such as site-site static structure factors are deduced\nfrom RISM. The results include the temperature-density(pressure) dependence of\ntranslational diffusion coefficients D and orientational relaxation times t for\nacetonitrile in water, methanol in water and methanol in acetonitrile, all in\nthe limit of infinite dilution. Calculations are performed over the range of\ntemperatures and densities employing the SPC/E model for water and optimized\nsite-site potentials for acetonitrile and methanol. The theory is able to\nreproduce qualitatively all main features of temperature and density\ndependences of D and t observed in real and computer experiments. In\nparticular, anomalous behavior, i.e. the increase in mobility with density, is\nobserved for D and t of methanol in water, while acetonitrile in water and\nmethanol in acetonitrile do not show deviations from the ordinary behavior. The\nvariety exhibited by the different solute-solvent systems in the density\ndependence of the mobility is interpreted in terms of the two competing origins\nof friction, which interplay with each other as density increases: the\ncollisional and dielectric frictions which, respectively, increase and decrease\nwith increasing density.",
"arxiv_id": "physics/0502128",
"authors": [
"A. E. Kobryn",
"T. Yamaguchi",
"F. Hirata"
],
"categories": [
"physics.chem-ph"
],
"doi": "10.1063/1.1884998",
"journal_ref": "J. Chem. Phys. 122 (2005) 184511",
"title": "Site-site memory equation approach in study of density/pressure dependence of translational diffusion coefficient and rotational relaxation time of polar molecular solutions: acetonitrile in water, methanol in water, and methanol in acetonitrile",
"url": "https://arxiv.org/abs/physics/0502128"
},
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