Universal scaling of potential energy functions describing intermolecular interactions. II. The halide-water and alkali metal-water interactions

Jasper C Werhahn; Dai Akase; Sotiris S Xantheas

doi:10.1063/1.4891820

Universal scaling of potential energy functions describing intermolecular interactions. II. The halide-water and alkali metal-water interactions

J Chem Phys. 2014 Aug 14;141(6):064118. doi: 10.1063/1.4891820.

Authors

Jasper C Werhahn¹, Dai Akase², Sotiris S Xantheas³

Affiliations

¹ Physik-Department E11, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany.
² Center for Quantum Life Sciences and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
³ Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, USA.

PMID: 25134562
DOI: 10.1063/1.4891820

Abstract

The scaled versions of the newly introduced [S. S. Xantheas and J. C. Werhahn, J. Chem. Phys. 141, 064117 (2014)] generalized forms of some popular potential energy functions (PEFs) describing intermolecular interactions--Mie, Lennard-Jones, Morse, and Buckingham exponential-6--have been used to fit the ab initio relaxed approach paths and fixed approach paths for the halide-water, X(-)(H2O), X = F, Cl, Br, I, and alkali metal-water, M(+)(H2O), M = Li, Na, K, Rb, Cs, interactions. The generalized forms of those PEFs have an additional parameter with respect to the original forms and produce fits to the ab initio data that are between one and two orders of magnitude better in the χ(2) than the original PEFs. They were found to describe both the long-range, minimum and repulsive wall of the respective potential energy surfaces quite accurately. Overall the 4-parameter extended Morse (eM) and generalized Buckingham exponential-6 (gBe-6) potentials were found to best fit the ab initio data for these two classes of ion-water interactions. The fitted values of the parameter of the (eM) and (gBe-6) PEFs that control the repulsive wall of the potential correlate remarkably well with the ionic radii of the halide and alkali metal ions.