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Sumanta Bhandary, M. Schüler, P. Thunström, I. Di Marco, B. Brena, O. Eriksson, T. Wehling, B. Sanyal:
"Correlated electron behavior of metal-organic molecules: Insights from density functional theory combined with many-body effects using exact diagonalization";
Physical Review B, 93 (2016), 155158.

A proper theoretical description of the electronic structure of the 3d orbitals in the metal centers of functional metalorganics is a challenging problem. We apply density functional theory and an exact diagonalization method in a many-body approach to study the ground-state electronic configuration of an iron porphyrin (FeP) molecule. Our study reveals that the consideration of multiple Slater determinants is important, and FeP is a potential candidate for realizing a spin crossover due to a subtle balance of crystal-field effects, on-site Coulomb repulsion, and hybridization between the Fe-d orbitals and ligand N-p states. The mechanism of switching between two close-lying electronic configurations of Fe-d orbitals is shown. We discuss the generality of the suggested
approach and the possibility to properly describe the electronic structure and related low-energy physics of the whole class of correlated metal-centered organometallic molecules.

http://dx.doi.org/10.1103/PhysRevB.93.155158