The ground-state projection in PbE ensures that every subsystem consists of a set of occupied orbitals localized in the region associated with that subsystem, and, in addition, of the entire (supersystem) set of virtual orbitals. This has the effect that even outgoing charge-transfer excitations for each subsystem can be described. Because of this, the method is also suited to described couplings between local excitations and charge-transfer excitations, for which it gives results in line with methods like the fragment excitation difference (FED)-fragment charge difference (FCD) diabatization procedure . Since this exact sTDDFT provides a robust reference for the quantification of environment effects, it was also applied in a proof-of-principle study to describe environmental response contributions also known as off-resonance excitonic couplings . In that work, also a new type of virtual-orbital localization procedure was employed, based on earlier work by Claudino and Mayhall , in order to separate the effect of local and inter-subsystem charge-transfer excitations.