Dynamical Hubbard approach to correlated materials: the case of transition-metal monoxides

Electronic correlations beyond static mean-field theories are of fundamental importance in describing the properties of complex materials - such as transition-metal oxides - where the low-energy physics is driven by localized d or f electrons. Here, we show that it is possible to capture these correlations with a local and dynamical self energy, extending to the spin-polarized and multi-site case our recently introduced dynamical Hubbard functional formulation. We apply this formalism to the prototypical transition-metal monoxide series of MnO, FeO, CoO, and NiO in their ground state, finding excellent agreement with experiments for the spectral properties. The results are comparable or improved with respect to state-of-the-art theories, both for the densities of states and for the spectral functions - including band renormalization and spectral weight transfer - in a numerically efficient and physically transparent treatment of correlations amenable to the study of realistic, complex materials.