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Importance of accurate dynamic polarizabilities for the ionic dispersion interactions of alkali halides

Parsons, D.F.ORCID: 0000-0002-3956-6031 and Ninham, B.W. (2010) Importance of accurate dynamic polarizabilities for the ionic dispersion interactions of alkali halides. Langmuir, 26 (3). pp. 1816-1823.

Link to Published Version: http://dx.doi.org/10.1021/la902533x
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Abstract

Ab initio quantum mechanical calculations of the dynamic polarizability of alkali metal and halide ions are performed as a function of imaginary frequency. Electron correlation is shown to provide a significant correction to ionic polarizabilities. Ab initio ion-surface dispersion coefficients are compared, with single- and multimode London approximations. The commonly employed single-mode model with the characteristic frequency taken from the ionization potential of the ion is shown to be inadequate, underestimating dispersion forces with an average error around 40% or as high as 80% for halide ions. Decomposition of the polarizability data into five modes covers the major modes of each ion adequately (four modes for Li+). Illustrative calculations of surface potentials at the mica surface in aqueous alkali halide electrolytes are made. Charge reversal is obtained with the more polarizable cations, K+ and Rb +. The error in the single-mode ionization potential models is seen as a strong shift in the surface potential from negative toward positive values.

Item Type: Journal Article
Publisher: American Chemical Society
Copyright: © 2009 American Chemical Society.
URI: http://researchrepository.murdoch.edu.au/id/eprint/27277
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