Just outside of the cavity, it is observed that there is a slightly higher density of the Cl -ions than the Na + cations. Integrating to a distance of 5.5 Å the coordination number of Cl -is 0.7 higher than that of Na + . This leads to a dipole layer in the vicinity of a cavity of 4 Å size. When the solute ion is present at the center of the cavity as shown in panel c, however, both solvent ions exhibit charge-symmetrical behavior, as evidenced by the overlaps in the IS RDFs.