Journal article
A continuum solvent model of ion–ion interactions in water
Physical Chemistry Chemical Physics, Vol.16(40), pp.22014-22027
2014
Abstract
The calculation of ion-ion interactions in water is a problem of long standing importance. Modelling these interactions is a prerequisite to explaining Hofmeister (specific ion) effects. We here generalize our solvation model of ions to calculate the free energy of two ions in water as a function of separation. The same procedure has previously been applied to calculate ion interactions with the air-water interface successfully. The Conductor like Screening Model (COSMO) is used. This treats the ions on a quantum mechanical level and calculates numerically the electrostatic response of the surrounding solvent. Estimates of the change in the cavity formation energy and the change in the ion-water dispersion energy as the ions approach are included separately. The calculated interaction potentials are too attractive and this is a significant issue. However, they do reproduce the affinity of similarly sized ions for each other, which is a crucial property of these potentials. They are also oscillatory, another important property. We normalize the potentials to reduce the over-attraction, and good correlation with experimental values is achieved. We identify the driving contributions to this like-prefers-like behaviour. We then put forward a plausible hypothesis for the over-attraction of the potentials. An agreeable feature of our approach is that it does not rely on salt specific parameters deliberately adjusted to reproduce experimental values.
Details
- Title
- A continuum solvent model of ion–ion interactions in water
- Authors/Creators
- T.T. Duignan (Author/Creator)D.F. Parsons (Author/Creator)B.W. Ninham (Author/Creator)
- Publication Details
- Physical Chemistry Chemical Physics, Vol.16(40), pp.22014-22027
- Publisher
- Royal Society of Chemistry
- Identifiers
- 991005542550307891
- Copyright
- © 2014 the Partner Organisations.
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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- Citation topics
- 2 Chemistry
- 2.89 Ionic, Molecular & Complex Liquids
- 2.89.677 Liquid Water
- Web Of Science research areas
- Chemistry, Physical
- Physics, Atomic, Molecular & Chemical
- ESI research areas
- Chemistry