However, for outer-sphere reactions and semiconductor electrodes these two approaches diverge. In outer-sphere reactions, E DF T f no longer "belongs" to the electrode and consequently the Fermi level is not uniquely determined by the electrode, whereas ϕ M is locally defined within the electrode and the outer-sphere couple has no effect on it. Therefore, ϕ M can be independently controlled from the solvent phase as in experiments and according to the general definition of electrode potentials (Eq. ( )). On the other hand, For semiconductor electrodes, the main advantage of using ϕ M is that it can be continuously controlled and that it is less sensitive to the number of electrons in the system. While E DF T f varies discontinuously in the band gap region and exhibits large jumps when the number of electrons is changed, variations in ϕ M are smaller and smoother. These differences between the two methods arise from the use of two distinct definitions of single-electrode potentials: