The functional dependence of the energy surfaces is qualitatively clear. Although the TPSSh-D3 functional had the best agreement with WFT for ∆E S 0 -T 0 , the S 0 and T 0 states are not nearly degenerate on the planar T 0 structure. The TPSSh-D3 closed-shell singlet state is 6.7 kcal/mol higher in energy than the triplet on the planar T 0 structure, following a state crossing near the structure of intermediate 3 (INT3). No state crossing is observed on the XMS-CASPT2 LIIC surface. On the other hand, PBE-D3 had the largest ∆E S 0 -T 0 but the shape of the LIIC is more similar to the one from WFT (no state crossing, a ground state singlet, and a near degeneracy of the two states on the planar structure). PBE0-D3 presents the worst case scenario where a state crossing is observed and the triplet spin state is the ground state. Moreover, the shape of the DFT S 0 surfaces are similar, but shifted higher in energy with respect to the triplet state as a function of increasing HF exchange (PBE has 0%, TPSSh has 10%, and PBE0 has 25% HF exchange). A similar functional dependence is observed for 5,10,15-triphenyl copper corrole (Figure -S32) and the TPSSh-D3 LIIC for the two lowest singlet and triplet states is included as supporting information on the TPSSh-D3 and XMS-CASPT2 geometries (Figure ).