Dynamical mean-field theory for transition metal dioxide molecules

The utility of the dynamical mean-field approximation in quantum chemistry is investigated in the context of transition metal dioxide molecules including $TiO_2$ and $CrO_2$. The choice of correlated orbitals and correlations to treat dynamically is discussed. The dynamical mean field solutions are compared to state of the art quantum chemical calculations. The dynamical mean-field method is found to capture about 50\% of the total correlation energy, and to produce very good results for the d-level occupancies and magnetic moments. We also present the excitation spectrum in these molecules which is inaccessible in many wave-function based methods. Conceptual and technical difficulties will be outlined and discussed.