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Abstract: The electronic and magnetic properties of many strongly-correlated systemsare controlled by a limited number of states, located near the Fermi level andwell isolated from the rest of the spectrum. This opens a formal way forcombining the methods of first-principles electronic structure calculations,based on the density-functional theory DFT, with many-body models, formulatedin the restricted Hilbert space of states close to the Fermi level. The core ofthis project is the so-called -realistic modeling- or the construction of themodel many-body Hamiltonians entirely from the first principles. Such aconstruction should be able to go beyond the conventional local-densityapproximation LDA, which typically supplements the density-functional theory,and incorporate the physics of Coulomb correlations. It should also provide atransparent physical picture for the low-energy properties of stronglycorrelated materials. In this review article, we will outline the basic ideasof such a realistic modeling. The entire procedure will be illustrated on theseries of examples, including the distorted transition-metal perovskite oxides,the compounds with the inversion symmetry breaking caused by the defects, andthe alkali hyperoxide KO2, which can be regarded as an analog ofstrongly-correlated systems where the localized electrons reside on themolecular orbitals of the O2- dimer. In order to illustrate abilities of therealistic modeling, we will also consider solutions of the obtained low-energymodels for a number of systems, and argue that it can be used as a powerfultool for the exploration and understanding of properties of strongly correlatedmaterials.



Autor: I. V. Solovyev

Fuente: https://arxiv.org/







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