What computational chemistry and magnetic resonance reveal concerning the oxygen evolving centre in Photosystem II

We present density functional theory calculations of the electronic structure, magnetic coupling and 55Mn hyperfine structure of models of the Mn4CaO5 oxygen-evolving complex of the Photosystem II holoenzyme. These data suggest a 'Coupled Dimer' model of magnetic interaction consistent with experimental 55Mn hyperfine data.230