Below, we express all energies and electrostatic potentials in eV and equation reads μi e = µ i e -ϕ i . Given that µ i e is constant for a given phase and material, the inner potential of a given phase determines the applied electrode potential of either bath or a working electrode, M . The electrochemical potential of electrons within the electrode M is also directly proportional to the Fermi level of the given phase as μM e = E f . While experiments are routinely performed under constant potential conditions and referenced against well-defined reference electrodes, realizing constant potential atomistic simulations has been very challenging and several schemes for controlling the applied poten- tial have been developed. Current methods to simulate the applied electrode potential can be roughly divided into three categories: electronic structure methods within the grand-canonical ensemble density functional theory (GCE-DFT) , classical force field methods, and finite-field methods, which can be used either with DFT or classical potentials. GCE-DFT simulations typically consider a single electrode and work on the singleelectrode potential scale to fix μM e providing an exact framework for treating systems at constant electrochemical potential. In particular, the grand canonical free energy as well as other (thermodynamic) expectation values from GCE-DFT are formally exact and unique for given external (electrode) potential with an explicit dependence on μM e . As discussed in detail in Section 2. e is proportional to the electrode work function or Fermi level readily available from any periodic DFT implementation. Given this generality and ability to work with just a single electrode, the Fermi level -based GCE-DFT has become widely adopted for modelling electrochemical thermodynamics and kinetics at fixed μM e . Essentially, all GCE-DFT approaches can be seen as finite-size corrections needed to fix the electrode potential in small simulation cells. If a large enough simulation cell is used, the canonical and GCE-DFT simulations would be equally applicable for electrochemical simulations.