This strategy gives access to accurate long-range charge-transfer (CT) excitation energies, as they are effectively computed as a difference in the energies of two electronic states. It could also be shown that the long-range behavior has the correct (-1/R) distance behavior and reaches the correct limit. Moreover, it has been demonstrated there that electronic couplings between locally excited (LE) and CT states are accessible when starting from a ∆SCF-DFT solution for one of the subsystems involved (rather than from the neutral ground state). It hence offers a valuable alternative to subsystem TDDFT (see Section 6.2.2) for processes involving inter-subsystem charge-transfer phenomena.