Key points are not available for this paper at this time.
Geometries and force-fields of the low-lying spin states of iron(II) porphine are calulated with nonlocal density functional methods. The ground state is identified as the 3A2g state. It is shown that the Fe atom is in the porphine plane for all spin states, but that the high-spin state potential surface intersects the triplet-state potential surfaces along the doming-mode coordinate when the iron atom is displaced about 0.4 Å from the NNNN plane. This intersection is the result of an electron occupying the antibonding dx2-y2 orbital in the quintet states. The doming mode of the porphine is predicted to be at 71 cm-1, close to the 75 cm-1 frequency determined from coherent reaction dynamics in myoglobin.
Kozlowski et al. (Tue,) studied this question.