Figure 1

Optimized structures and bond lengths (Å) of most stable isomers of (a) ${\mathrm{Cl}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_4$, (b) ${\mathrm{Li}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_5$, (c) ${\mathrm{OH}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_4$, (d)  ${\mathrm{Na}}^{+}({\mathrm{H}}_2\mathrm{O}{)}_5$, and (e) ${\mathrm{H}}_3{\mathrm{O}}^{+}({\mathrm{H}}_2\mathrm{O}{)}_6$ and ESP for (f) ${\mathrm{OH}}^{-}({\mathrm{H}}_2\mathrm{O})$ and (g) ${\mathrm{H}}_3{\mathrm{O}}^{+}({\mathrm{H}}_2\mathrm{O})$. ESP of ${\mathrm{OH}}^{-}({\mathrm{H}}_2\mathrm{O})$ and ${\mathrm{H}}_3{\mathrm{O}}^{+}({\mathrm{H}}_2\mathrm{O})$ ground states is mapped onto the electron density surface for the ground state. The color map shows the electrostatic potential energy (in hartrees) for the various colors. The red end of the spectrum shows the regions of highest stability for a positive test charge, while magenta/blue shows the regions of least stability for a positive test charge.Reuse & Permissions

Figure 2

Comparison of experimental and theoretical values of the Gibbs free energy $\Delta G_{n,n-1}$ for $X^{\pm }({\mathrm{H}}_2\mathrm{O}{)}_{n-1}+{\mathrm{H}}_2\mathrm{O}=X^{\pm }({\mathrm{H}}_2\mathrm{O}{)}_n$ reactions [(a),(b)] and the difference in the Gibbs free energy $\delta (j)$ between $j$-mers formed over core ions of opposite sign (water cation and water anion) (c). Curves and symbols of the same color refer to theoretical results and experimental data, respectively. Abbreviations DNT, MC, and QM refer to the dynamic nucleation theory [27], the Monte Carlo study [25] (four-point transferable intermolecular potential water), and the present study, respectively. Symbols L and S refer to core ions of indeterminate composition of 0.1 and 1 nm radius, respectively [27]. Subscripts “$+$” and “$-$” refer to the charge polarities. Experimental data for ${\mathrm{Li}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_n$ [42], ${\mathrm{Na}}^{+}({\mathrm{H}}_2\mathrm{O}{)}_n$ [42], ${\mathrm{OH}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_n$ [44], ${\mathrm{H}}_3{\mathrm{O}}^{+}({\mathrm{H}}_2\mathrm{O}{)}_n$ [40, 41], and ${\mathrm{Cl}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_n$ [43] were used. Experimental values of $\delta (j)$ [blue triangles in Fig. 2c] were calculated from the experimental data for ${\mathrm{H}}_3{\mathrm{O}}^{+}({\mathrm{H}}_2\mathrm{O}{)}_n$ [41] and ${\mathrm{OH}}^{-}({\mathrm{H}}_2\mathrm{O}{)}_n$ [44]. The calculations were performed at the ambient temperature of 298.15 K and ambient pressure of 101.3 KPa.Reuse & Permissions