The resulting γ sl > 0 as otherwise the bulk phases would spontaneously decompose to maximize the interfacial area. On the other hand, F solv can be either negative or positive as it measures the effective solvation energy of the metal surface per unit area. Note that F solv measures the surface-water interaction only and does not directly tell whether a surface is wetting or not because the contact angle (Eq. ( )) depends also on the properties of the water-vacuum and metal-vacuum interfaces.