Realistic Modeling of Complex Oxide Materials from the First Principles

General ideas and strategies of realistic modeling of strongly correlated systems are reviewed. The purpose of this approach is to construct a microscopic (for example, the Hubbard-type) model for the limited group of bands located near the Fermi level and derive parameters of this model entirely from the first-principles electronic structure calculations. Thus, the method combines the accuracy of the first-principle calculations with the transparency and physical insights of the model analysis. The abilities of the method are illustrated on a number of examples, including the origin of the multiferroicity in BiMnO₃, spin-orbital-lattice coupled phenomena in ABO₃ (where A= three-valent rare-earths element and B= Ti or V), and magnetism of KO₂. The latter compound can be regarded a rare example of strongly correlated system build from the magnetic oxygen molecules.