FIGURE 6.

Effect of ion size on the structure of water. (A) Hydration shell geometry, defined by the probability distribution of the angle φ formed by water oxygen-ion-water oxygen as described in the text, for ions in pure water. I⁻ data is intermediate to Cl⁻ and X⁻ and is omitted for clarity. (B) Hydration shell geometry distributions for Na⁺ in the aqueous phase (dashed line, as in A) and for those Na⁺ ions within the first headgroup phosphorus hydration shell. (C) ΔG of solvation, relative to a Na⁺ ion, of the three anion types, as a function of the vdW radius, σ.