Ion pair correlations due to interference between solvent polarizations induced in water

Banerjee, P and Bagchi, B (2020) Ion pair correlations due to interference between solvent polarizations induced in water. In: Journal of Chemical Physics, 152 (6).

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Abstract

Motions of two distinct ions can get correlated because the polarization induced by the ions can propagate through intervening water and can interfere with each other. This important aspect, which is not included in the continuum model based theories, has not been studied adequately. We calculate the effective force between two oppositely charged and similarly charged ions fixed in water as a function of separation distance R. At short separations, R less than 1.5 nm, the effective force vastly differs from the 1/ϵsR2 dependence advocated by the screened Coulomb's force law (SCFL), where ϵs is the static dielectric constant of the medium. This breakdown of the SCFL is shown to be due to the persistent interference between the polarizations created by the two charges in a manner similar to the vortex-antivortex pair formation in the XY model Hamiltonian. The distance dependence of dielectric constants, ϵs(R), extracted from our simulation exhibits interesting features and can be used in future modeling. In addition, we show that the force-force time autocorrelation between two neighboring ions decays differently at short separation and analyze the friction on the ion pair at different separation distances.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics Inc.
Additional Information:	Copyright of this article belongs to American Institute of Physics Inc.
Keywords:	Continuum mechanics; Polarization, Continuum Modeling; Effective forces; Model Hamiltonians; Separation distances; Short separations; Solvent polarization; Static dielectric constants; Vortex-antivortex pairs, Ions
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	06 Mar 2020 11:04
Last Modified:	06 Mar 2020 11:04
URI:	http://eprints.iisc.ac.in/id/eprint/64694

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