The first vertical excitation energies calculated with the ΔSCF approach at the DFT/PBE0-D3(BJ)/def2-TZVP and DFT/ωB97X-D/def2-TZVP levels of theory and the corresponding singlet–triplet gap for 1–3 (energies are given in eV).
| Molecule | E(S1 ← S0) | E(T1 ← S0) | ΔEST |
|---|---|---|---|
| PBE0 functional | |||
| 1 | 2.612 | 2.760 | −0.148 |
| 2 | 2.635 | 2.819 | −0.184 |
| 3 | 2.485 | —a | — |
| ωB97X-D functional | |||
| 1 | 2.807 | 3.111 | −0.304 |
| 2 | 2.801 | 3.105 | −0.304 |
| 3 | 2.715 | 3.021 | −0.306 |
a
The ΔSCF calculation did not converge.