Diffusion Enhancement in Core-softened fluid confined in nanotubes

Abstract

We study the effect of confinement in the dynamical behavior of a core-softened fluid. The fluid is modeled as a two length scales potential. This potential in the bulk reproduces the anomalous behavior observed in the density and in the diffusion of liquid water. A series of $NpT$ Molecular Dynamics simulations for this two length scales fluid confined in a nanotube were performed. We obtain that the diffusion coefficient increases with the increase of the nanotube radius for wide channels as expected for normal fluids. However, for narrow channels, the confinement shows an enhancement in the diffusion coefficient when the nanotube radius decreases. This behavior, observed for water, is explained in the framework of the two length scales potential.

17 pages, 8 figures, accept for publication at J. Chem. Phys

References in corpus (4)

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• Structural anomalies for a three dimensional isotropic core-softened potential
• Strong Correlations and Fickian Water Diffusion in Narrow Carbon Nanotubes
• Structural anomalies of fluids: Origins in second and higher coordination shells

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