For TD-DFT, one might define separate PRs for the electron and the hole: Following appropriate coordinate transformations, each of these PRs involves a summation over x 4 µν , as in the general definition of Eq. (4.20). In the idealized case of the states presented in Fig. , one finds that the four localized states are characterized by PR e-h = 1 and are thus distinguishable from the four delocalized states, for which PR e-h = 2. This is indicated in Table .