has played a central role in the ALMO-based energy decomposition analysis scheme for excited-state intermolecular complexes (i.e., exciplexes and excimers). The reference orbitals for an ALMO-TDA calculation are prepared via the variational optimization of ALMOs, i.e., minimization of the KS-DFT energy with respect to the MO coefficient matrix (C) subject to the constraint that C is block-diagonal by fragments. This procedure is also known as "self-consistent field for molecular interactions" (SCF-MI), and "blocked localized wavefunction" (BLW). With the ALMOs prepared, a singly excited state under the ALMO-TDA framework can be represented as