Issue 9, 2017

Real single ion solvation free energies with quantum mechanical simulation

Abstract

Single ion solvation free energies are one of the most important properties of electrolyte solutions and yet there is ongoing debate about what these values are. Only the values for neutral ion pairs are known. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi-chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A method to correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energies into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Our research suggests that lithium's solvation free energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model.

Graphical abstract: Real single ion solvation free energies with quantum mechanical simulation

Supplementary files

Article information

Article type
Edge Article
Submitted
12 May 2017
Accepted
26 May 2017
First published
04 Jul 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2017,8, 6131-6140

Real single ion solvation free energies with quantum mechanical simulation

T. T. Duignan, M. D. Baer, G. K. Schenter and C. J. Mundy, Chem. Sci., 2017, 8, 6131 DOI: 10.1039/C7SC02138K

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