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Author Martínez-Ruiz, F. J. ♦ Blas, F. J. ♦ Moreno-Ventas Bravo, A. I.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ BINARY MIXTURES ♦ COMPUTERIZED SIMULATION ♦ DENSITY ♦ DESORPTION ♦ INTERACTIONS ♦ INTERFACES ♦ LIQUIDS ♦ MOLECULES ♦ MONTE CARLO METHOD ♦ PRESSURE DEPENDENCE ♦ SPHERICAL CONFIGURATION ♦ SURFACE TENSION ♦ TENSORS
Abstract We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules at the interface, a direct consequence of a combination of the weak dispersive interactions between unlike species of the symmetrical binary mixture, and the presence of an interfacial region separating the two immiscible liquid phases in coexistence.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-09-14
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 143
Issue Number 10


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