To generate R-U-and G-HF & CASSCF wavefunctions, and to obtain R-, U-, and G-CCSD(T) and FCI values, we have used PySCF 2.5.0. 86,87 At 4 points along the H-ring dissociation coordinates we struggled to converge on the correct UHF solution -for those points we used Q-Chem 6.2 to generate the UHF trial.