| 1. |
- Nilsson, Fredrik, et al.
(author)
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Recent progress in first-principles methods for computing the electronic structure of correlated materials
- 2018
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In: Computation. - : MDPI AG. - 2079-3197. ; 6:1
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Research review (peer-reviewed)abstract
- Substantial progress has been achieved in the last couple of decades in computing the electronic structure of correlated materials from first principles. This progress has been driven by parallel development in theory and numerical algorithms. Theoretical development in combining ab initio approaches and many-body methods is particularly promising. A crucial role is also played by a systematic method for deriving a low-energy model, which bridges the gap between real and model systems. In this article, an overview is given tracing the development from the LDA+U to the latest progress in combining the GW method and (extended) dynamical mean-field theory (GW+EDMFT). The emphasis is on conceptual and theoretical aspects rather than technical ones.
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| 2. |
- Seth, Priyanka, et al.
(author)
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Renormalization of effective interactions in a negative charge transfer insulator
- 2017
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In: Physical Review B. - 2469-9950. ; 96:20
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Journal article (peer-reviewed)abstract
- We compute from first principles the effective interaction parameters appropriate for a low-energy description of the rare-earth nickelate LuNiO3 involving the partially occupied eg states only. The calculation uses the constrained random-phase approximation and reveals that the effective on-site Coulomb repulsion is strongly reduced by screening effects involving the oxygen-p and nickel-t2g states. The long-range component of the effective low-energy interaction is also found to be sizable. As a result, the effective on-site interaction between parallel-spin electrons is reduced down to a small negative value. This validates effective low-energy theories of these materials that were proposed earlier. Electronic structure methods combined with dynamical mean-field theory are used to construct and solve an appropriate low-energy model and explore its phase diagram as a function of the on-site repulsion and Hund's coupling. For the calculated values of these effective interactions, we find that in agreement with experiments, LuNiO3 is a metal without disproportionation of the eg occupancy when considered in its orthorhombic structure, while the monoclinic phase is a disproportionated insulator.
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| 3. |
- Werner, Philipp, et al.
(author)
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Dynamical screening in La2CuO4
- 2015
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 91:12
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Journal article (peer-reviewed)abstract
- We show that the dynamical screening of the Coulomb interaction among Cu-d electrons in high-Tc cuprates is strong and that a proper treatment of this effect is essential for a consistent description of the electronic structure. In particular, we find that ab initio calculations for undoped La2CuO4 in the paramagnetic phase yield an insulator only if the frequency dependence of the Coulomb interaction and the interatomic interaction between p and d electrons are taken into account. We also identify a collective excitation in the screened interaction at 9 eV, which is rather localized on the copper site, and which is responsible for a satellite structure at energy -13 eV, located below the p bands.
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