Simulating Monovalent and Divalent Ions in Aqueous Solution Using a Drude Polarizable Force Field

An accurate representation of ion solvation in aqueous solution is critical for meaningful computer simulations of a broad range of physical and biological processes. Polarizable models based on classical Drude oscillators are introduced and parametrized for a large set of monatomic ions including cations of the alkali metals (Li+, Na+, K+, Rb+, and Cs+) and alkaline earth elements (Mg2+, Ca2+, Sr2+, and Ba2+) along with Zn2+ and halide anions (F−, Cl−, Br−, and I−). The models are parametrized, in conjunction with the polarizable SWM4-NDP water model [Lamoureux et al. Chem. Phys. Lett. 2006, 418, 245], to be consistent with a wide assortment of experimentally measured aqueous bulk thermodynamic properties and the energetics of small ion−water clusters. Structural and dynamic properties of the resulting ion models in aqueous solutions at infinite dilution are presented.