Electronic excess charge distribution As evident from Fig. , the central difference between DFT and FF simulations is the distribution of electronic excess charge ρ electrode where the former are characterized by the predominant localization of ρ electrode in the ∼ 5 Å thick contact region between metal and water, and the latter by its localization exclusively on the first metal layer. The detailed differences between the methods can be seen more clearly in the left-most panel in Fig. a, which also includes ρ electrode as obtained from a DFT-HBG computation in vacuum and so without explicit interfacial water present. In the right-most panel of Fig. , we also report corrected excess charge densities ρ corrected electrode , where artificial density contributions in bulk water and the metallic slab were removed and the remaining charge distribution is appropriately renormalized. The agreement between ρ corrected electrode (or equally ρ electrode ) for DFT-HBG and DFT-PCH suggests that both are credible estimates for the intrinsic electronic bias charge distribution at the Pt(111)-water interfaces. Most importantly, both DFT methods show a sizable second density peak in the region z = 2.5-5.5 Å in Fig. a, and so entirely within the first water layer. This evident charge leakage into the water region at Pt(111) is qualitatively and quantitatively different from the known generic electron leakage into the vacuum region outside a metallic surface (cf. DFT-HBG vacuum simulations in Fig. ) the importance of which has been considered in previous works .