Whereas the calculations discussed above were performed at CASSCF and CASPT2 geometries, we have also optimized the geometries of the local minima on S 0 and S 1 , and the S 1 /S 0 minimum-energy crossing points (MECPs), using SF-TDDFT, LR-TDDFT, and LR-TDDFT/TDA; results are depicted in Fig. . For the local minima these three methods predict almost identical geometries. Automated optimization of MECPs fails at the LR-ωB97X level, due to triplet instabilities, there is no such difficulty when the TDA is applied. (Other results suggest that triplet instabilities are commonplace in bond-breaking regions of the potential energy surface, making the TDA "a practical necessity" for photochemical simulations. ) MECP geometries optimized at the LR-ωB97X/TDA and SF-BH&HLYP levels agree with each other very well, and also agree qualitatively with MS-CASPT2 results. Table I summarizes the relative energies of the various critical points shown in Fig. . Overall, the energies computed at the three DFT levels agree qualitatively with each other and with multistate (MS-)CASPT2 results. The DFT methods overestimate the vertical excitation energy as compared to MS-CASPT2, especially in the case of LR-ωB97X/TDA. Among the three MECPs considered here, all methods predict that the one with a twisted C 2 =C 3 double bond is lowest in energy; this is the structure labeled MECP(C 2 C 3 ) in Fig. and. The SF-BH&HLYP method places the three MECP a bit higher in energy as compared to LR-ωB97X/TDA. However, if one considers the energetics relative to the S 1 state at Franck-Condon region, the SF-BH&HLYP results are more consistent with the MS-CASPT2 results.