Quantitative many-body electronic structure of CaCuO₂ and LaNiO₂ from all-orbital DMFT

Dynamic mean-field theory (DMFT) with a downfolded correlated space has been widely used to study the many-body electronic structure of high T_c cuprate superconductors and their analog nickelates. Yet, different downfolding of correlated space from various localization schemes has yielded significantly different quasiparticle mass renormalization for both parent compounds and has even led to qualitatively different predictions in NdNiO2 over the importance of Hund’s and charge transfer physics [1]. To quantitatively capture the electron correlations, we applied a recently developed all-orbital GW+DMFT theory to CaCuO₂ and LaNiO₂ in the paramagnetic phase where all valence and virtual orbitals within a unit cell are included in the correlated space without downfolding. With an active-space DMRG solver suited to capture strong correlations, the calculated quasiparticle mass renormalization agrees to an order of magnitude better accuracy across correlated space from three different localizations compared to the downfolded DMFT results. Furthermore, we provide insights on downfolding by analyzing the importance of degrees of freedom near the Fermi level.

[1] Karp, J., Hampel, A., & Millis, A. J. (2021). Physical Review B, 103(19), 195101.