Since the localization of orbitals is used as the mapping criterion in the following, consistent orbital spaces along the reaction coordinate are needed as for the DOS scheme. For the latter, an orbital alignment procedure based on the framework of intrinsic atomic orbitals (IAOs) by was proposed in earlier work from our lab. The occupied orbitals of, e.g., structure A are localized in order to be used as template orbitals characterized by their orbital-wise IAO charges q A Ii . Each orbital of structure B is then rotated, i.e. aligned, to a template orbital by minimizing the squared difference in partial charges that correspond according to the atom map,