%A Hirayama,Motoaki %A Nomura,Yusuke %A Arita,Ryotaro %D 2022 %J Frontiers in Physics %C %F %G English %K nickelate superconductivity,Density Functional Theory,GW approximation,ab initio downfolding,multi-orbital Hubbard model %Q %R 10.3389/fphy.2022.824144 %W %L %M %P %7 %8 2022-February-23 %9 Original Research %# %! GW-based downfolding for nickelate superconductors %* %< %T Ab Initio Downfolding Based on the GW Approximation for Infinite-Layer Nickelates %U https://www.frontiersin.org/articles/10.3389/fphy.2022.824144 %V 10 %0 JOURNAL ARTICLE %@ 2296-424X %X We derive an effective three-orbital model for the infinite-layer nickelates based on the band structure obtained by the GW approximation (GWA), where we consider the Ni 3dx2y2 and O 2p orbitals forming the σ-bond. In the GWA, the self-energy correction to the local density approximation (LDA) increases the energy difference between Ni 3dx2y2 and O 2p, which reduces the bandwidth of the antibonding 3dx2y2 orbitals. The isolation of the Ni 3dx2y2 around the Fermi level suppresses the screening effect. As a result, the correlation effect becomes more significant than that in the model constructed by the LDA-based downfolding. Furthermore, the Mott-Hubbard type character is enhanced in the GWA-based effective model, because the charge-transfer energy increases more rapidly compared to the increase in the interaction parameters.