The presence of open-shell transition metal centers adds substantial complexity to quantum-chemical problems. While density-functional theory provides a reasonably good treatment of dynamic and near-degeneracy correlation in transition metal-containing systems, few ab initio methods are able to do so for relatively large real-life systems, which translates to a fertile field for methods development and testing.
Within bioinorganic chemistry, three main lines of theoretical studies will be pursued. (1) We will investigate diverse aspects of heme-diatomic interactions, from fundamental aspects of bonding and spectroscopy to studies of the structure and dynamics of key heme-based sensors such as soluble guanylate cyclase. With accurate energetics, we will obtain a much better understanding of heme-based sensing and signal transduction compared to the present situation. (2) Coordination chemistry of porphyrin-type ligands, with emphasis on high-valent transition-metal complexes. We will study a number of theoretical problems such as that of accurately computing the energetics of different low-lying states of transition-metal complexes (where density-functional theory often fails), reaction energetics, calculations of excited states (electronic spectra), and resonance Raman spectra. (3) Theoretical modeling of core-level spectroscopy (XPS and XAS) of problems in chemical structure, bonding, and dynamics. These spectroscopic methods can be used to characterize high-valent transition-metal compounds, mixed-valent materials and low-barrier hydrogen bonds.