GC-DFT thereby offers an exact treatment of electrochemical thermodynamics as function of the electrode potential: Ω[ρ μe ; μe ] = Ω(μ e ). Currently, GC-DFT implementations are available in various solid state DFT packages and can be rather routinely used for studying metallic systems as a function of potential. Most GC-DFT implementations use either the Fermilevel or the work function to model the single electrode potential on the vacuum scale (Eq. 2). Using the Fermi level to account for the electrode potential is, however, problematic with currently used slab models because the Fermi level cannot be continuously altered across the band gap region. The use of the recent constant inner potential (CIP-)DFT circumvents this difficulty and allows continuous control over the electrode potential on the solvent reference scale (Eq. ( )).