Density functional theory calculations, in both the high-spin and broken symmetry approximations, have been conducted on models of the diiron(II) ferroxidase complex of human H ferritin. Initial configurations were chosen from previous experimental and theoretical structures of the dizinc complex. The diiron complexes show no significant deviation in ligand or metal positions from the corresponding dizinc complexes, even maintaining similar structures through an extensive reorganization, and thus the often-made assumption of homology between Fe(II) and Zn(II) is supported. Geometry differences between diiron complexes calculated in the high-spin and broken symmetry approximations are also found to be minor. (C) 2011 Elsevier B.V. All rights reserved.