Prior studies have shown differences in barrier heights, spin state energies, i.e., spin splitting energies , and SCO behavior to be dependent on the amount of Hartree-Fock (HF) exchange (aHF) incorporated in a density functional. In fact, a study 103 of homoleptic Fe(II/III) complexes with the RPBE GGA functional suggested that RPBE 104 overstabilizes LS states by ca.