A continuum model of solvation energies including electrostatic, dispersion, and cavity contributions

Timothy T. Duignan, Drew F. Parsons*, Barry W. Ninham

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    75 Citations (Scopus)

    Abstract

    Physically accurate continuum solvent models that can calculate solvation energies are crucial to explain and predict the behavior of solute particles in water. Here, we present such a model applied to small spherical ions and neutral atoms. It improves upon a basic Born electrostatic model by including a standard cavity energy and adding a dispersion component, consistent with the Born electrostatic energy and using the same cavity size parameter. We show that the well-known, puzzling differences between the solvation energies of ions of the same size is attributable to the neglected dispersion contribution. This depends on dynamic polarizability as well as size. Generally, a large cancellation exists between the cavity and dispersion contributions. This explains the surprising success of the Born model. The model accurately reproduces the solvation energies of the alkali halide ions, as well as the silver(I) and copper(I) ions with an error of 12 kJ mol-1 (±3%). The solvation energy of the noble gases is also reproduced with an error of 2.6 kJ mol-1 (±30%). No arbitrary fitting parameters are needed to achieve this. This model significantly improves our understanding of ionic solvation and forms a solid basis for the investigation of other ion-specific effects using a continuum solvent model.

    Original languageEnglish
    Pages (from-to)9421-9429
    Number of pages9
    JournalJournal of Physical Chemistry B
    Volume117
    Issue number32
    DOIs
    Publication statusPublished - 15 Aug 2013

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