  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 3$d_{x^2-y^2}$ and O 2$p$ orbitals forming the $\sigma$-bond.
In the GWA, the self-energy correction to the local density approximation (LDA)
increases the energy difference between Ni $3d_{x^2-y^2}$ and O $2p$, which
reduces the bandwidth of the antibonding 3$d_{x^2-y^2}$ orbitals. The isolation
of the Ni $3d_{x^2-y^2}$ 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.
