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Ions in water: Role of attractive interactions in size dependent diffusivity maximum

Borah, Bhaskar J and Yashonath, S (2010) Ions in water: Role of attractive interactions in size dependent diffusivity maximum. In: Journal of Chemical Physics, The, 133 (11).

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Abstract

A molecular dynamics study of model ions in water is reported. The van der Waals diameter of both the cations and anions is varied. We have carried out two sets of simulations-with and without dispersion interaction-between the ion and water. Self-diffusivity of the ions exhibits an anomalous maximum as a function of the van der Waals diameter for both these sets. This existence of a maximum in self-diffusivity when there is no dispersion interaction between the ion and the water is attributed to the attractive term from electrostatic interactions. Detailed analysis of this effect shows that the solvent shell is more strongly defined in the presence of dispersion interactions. A smaller ion exhibits biexponential decay while a single exponential decay is seen for the ion with maximum diffusivity in the self-part of the intermediate scattering function. The solvent structure around the ion appears to determine much of the dynamics of the ion. Interesting trends are seen in the activation energies and these can be understood in terms of the levitation effect. (C) 2010 American Institute of Physics. doi:10.1063/1.3481656]

Item Type: Journal Article
Additional Information: Copyright of this article belongs to American Institute of Physics.
Keywords: ionic conductivity;molecular dynamics method;self-diffusion; van der Waals forces;water
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Others
Date Deposited: 29 Nov 2010 11:33
Last Modified: 01 Mar 2012 08:13
URI: http://eprints.iisc.ernet.in/id/eprint/34069

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