Table summarizes the calculated vertical transitions of 2', 3', and 4' in the low-energy region. The low-energy peak labeled A in the spectra of all NCs (Figure ) was attributed to the HOMO-2(D) or HOMO-3(D) to LUMO(Pz) transition. Transitions from HOMO or HOMO-1 to LUMO are forbidden because they involve transitions from one superatomic P orbital to another without changes in the angular momenta of the superatomic orbitals. The A peak of 3' was blue-shifted from that of 2'. The peak labeled B was also blue-shifted to B1 as a consequence of TDT-based bridging (Figure ). In the case of the experimental absorption spectrum, this peak was at approximately 2 eV and was also blue-shifted as a result of TDT bridging (Figure and). Peak B was associated with several transitions, most notably the HOMO or HOMO-1 → LUMO+1 or LUMO+2 transitions (Table ). Peak B1 was also attributed to transitions between similar orbitals (Table ). In contrast, newly emerged peak B2 was attributed to the HOMO or HOMO-1 → LUMO+3 or LUMO+4 transition. The degenerate LUMO+3 and LUMO+4 orbitals of 3' and 4' were derived from the non-degenerate LUMO+3 and LUMO+4 orbitals of 2' (Figure ). The above findings established that TDT bridging produced orbital degeneracy as a consequence of symmetry enhancement and the stabilization of orbitals other than the LUMO, resulting in new absorption properties.