The phenol/phenoxy pair has been studied extensively with different computational approaches. The consensus is that PCET in this system does not proceed through charge-separated states. The reactant and product minima corresponding to the topleft and bottom-right corners of the square scheme are depicted in Figure PC and ET dimension. In correspondence with the square scheme the product minimum lies in between the ⃗ p and ⃗ q vectors. The non-orthogonality of these vectors implies that ET and PT cannot be separated as pure processes. In other words, they are coupled.