A Haldane-Anderson impurity model study for the spin- and charge-states of iron in heme proteins

To understand the spin and charge properties of iron(II) hemo-proteins like myoglobin, we formulated a Haldane-Anderson impurity model within the closed-shell DFT-hybrid-GGA approximation. We employed a mean-field approximation to solve a simple model of myoglobin active site, the iron porphyin-imidazol complex FeP(Im), which was found to reproduce some of the known spin-charge states of myoglobin. We also computed the spin-charge phase diagram of iron in FeP(Im) with and without O2 attached to the central iron, and found that the spin-charge states for FeP(Im) is much more sensitive to the local correlations than that for FeP(Im)(O2).