CONSISTENT LDA+DMFT APPROACH TO THE ELECTRONIC STRUCTURE OF TRANSITION METAL OXIDES: CHARGE TRANSFER INSULATORS AND CORRELATED METALS
Nekrasov I.A., Pavlov N.S., Sadovskii M.V.

Received: October 1, 2012

DOI: 10.7868/S0044451013040113

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We discuss the recently proposed LDA+DMFT approach providing a consistent parameter-free treatment of the so-called double counting problem arising within the LDA+DMFT hybrid computational method for realistic strongly correlated materials. In this approach, the local exchange-correlation portion of the electron-electron interaction is excluded from self-consistent LDA calculations for strongly correlated electronic shells, e. g., d-states of transition metal compounds. Then, the corresponding double-counting term in the LDA+DMFT Hamiltonian is consistently set in the local Hartree (fully localized limit, FLL) form of the Hubbard model interaction term. We present the results of extensive LDA+DMFT calculations of densities of states, spectral densities, and optical conductivity for most typical representatives of two wide classes of strongly correlated systems in the paramagnetic phase: charge transfer insulators ( MnO, CoO, and NiO) and strongly correlated metals ( SrVO₃ and Sr₂ RuO₄). It is shown that for NiO and CoO systems, the LDA+DMFT approach qualitatively improves the conventional LDA+DMFT results with the FLL type of double counting, where CoO and NiO were obtained to be metals. Our calculations also include transition-metal 4s-states located near the Fermi level, missed in previous LDA+DMFT studies of these monooxides. General agreement with optical and the X-ray experiments is obtained. For strongly correlated metals, the LDA+DMFT results agree well with the earlier LDA+DMFT calculations and existing experiments. However, in general, LDA+DMFT results give better quantitative agreement with experimental data for band gap sizes and oxygen-state positions compared to the conventional LDA+DMFT method.