Effect of charge self-consistency in DFT+DMFT calculations for complex transition metal oxides

Abstract

We investigate the effect of charge self-consistency (CSC) in density-functional theory plus dynamical meanfield theory calculations compared to simpler "one-shot" calculations for materials where interaction effects lead to a strong redistribution of electronic charges between different orbitals or between different sites. We focus on two systems close to a metal-insulator transition (MIT), for which the importance of CSC is currently not well understood. Specifically, we analyze the strain-related orbital polarization in the correlated metal CaVO 3 and the spontaneous electronic charge disproportionation in the rare-earth nickelate LuNiO 3. In both cases, we find that the CSC treatment reduces the charge redistribution compared to cheaper one-shot calculations. However, while the MIT in CaVO 3 is only slightly shifted due to the reduced orbital polarization, the effect of the site polarization on the MIT in LuNiO 3 is more subtle. Furthermore, we highlight the role of the double-counting correction in CSC calculations containing different inequivalent sites.

Superconductivity and Antiferromagnetism in NdNiO$_2$ and CaCuO$_2$: A Cluster DMFT Study

“…which could particularly be an issue in a case of multiple correlated atoms [46]. A five orbital fully charge self consistent DFT+DMFT calculation on NdNiO 2 shows that the orbital occupancies do not change considerably from their DFT values [10].…”

“…Appendix D: double counting correction One of the major uncertainties in DFT+DMFT is the double counting correction, both the functional dependence on the density and which density to use [44][45][46]. For one shot DMFT calculations, it is unclear whether it is better to use the DFT density or DMFT density.…”

Wave functions, electronic localization, and bonding properties for correlated materials beyond the Kohn-Sham formalism

“…This is seen experimentally [37,38] and complimented by DFT + DMFT calculations [27,39]. There are a few material-specific mechanisms which the MIT has been attributed to such as the crystal field splitting [40][41][42][43] and confinement in the SrVO 3 layers [44].…”

Spatial inhomogeneity and the metal-insulator transition in Ca3(Ru1−xTix)2Lechermann1, Han2, Millis3 2020Phys. Rev. Research5000View full textAdd to dashboardCite

“…Note, in this respect, that a paramagnetic MIT was realized for single-layer Ca 2 RuO 4 with ∼ −320 meV for U = 3.1 eV in a previous one-shot DFT + DMFT calculation [21]. However, such one-shot approaches are known for two features compared to charge self-consistent DFT + DMFT [37,38], namely, tending to overestimate orbital polarizations and often realizing smaller critical U values. Furthermore, the MIT value of U = 4.25 eV for the defect supercell (see the green pentagon in Fig.…”