There are two interesting observations to be made from the interaction energy data in Fig. . Foremost is the fact that differences between the bulk and interfacial mean values E int for a given ion are small compared to the fluctuations in the instantaneous value of E int . Bulk values of E int are systematically (slightly) larger in magnitude than interfacial values, except for CN -, OCN -, and NO - 3 where the averages are essentially identical. In all cases, however, the difference between bulk and interfacial average values of E int is well within the standard deviation in either quantity; see the numerical values that are provided in Table . For the halides, the modest reductions in E int at the interface (up to 7-8 kcal/mol for bromide and iodide) are consistent with results from classical MD simulations indicating that the average ion-water interaction is reduced, for all of the halides, as the ion moves towards the interface . It should be noted that the simulations reported in Ref. indicate that the enthalpic portion of the potential of mean force is more favorable for the heavier halides at the interface, as compared to its value in bulk water. As such, the rather subtle differences between ion-water interactions that are documented in our quantum-mechanical calculations are more than compensated by ion-induced changes in the water-water interactions . This is consistent with our detailed structural analysis of the ions , which indicates very little change in the first-shell structure at the interface as compared to that in bulk water.