Fig. 1: Non-spin-polarized band structures calculated by density functional theory (DFT) and Wannier fitting.
a, b DFT-calculated band structures and 17 Wannier functions fitting of NdNiO2 (a) and CaCuO2 (b). The thick blue lines are DFT-calculated bands and the red thin lines are bands reproduced by the Wannier functions. The red dots show the Wannier projection onto Ni-\({d}_{{x}^{2}-{y}^{2}}\) and Cu-\({d}_{{x}^{2}-{y}^{2}}\) orbitals, respectively. c–e Band structures reproduced by Wannier functions in an energy window close to the Fermi level. The dots show the weights of Wannier projections onto Nd-\({d}_{3{z}^{2}-{r}^{2}}\) orbital (c), Nd-dxy orbital (d), and interstitial-s orbital (e). The coordinates of the high-symmetry points on the k-path are Γ(0,0,0)-X(0.5,0,0)-M(0.5,0.5,0)-Γ(0,0,0)-Z(0,0,0.5)-R(0.5,0,0.5)-A(0.5,0.5,0.5)-Z(0,0,0.5). The Fermi level EF (black dashed line) is shifted to zero energy. f–h An iso-value surface of the Wannier functions of Nd-\({d}_{3{z}^{2}-{r}^{2}}\) orbital (f), Nd-dxy orbital (g), and interstitial-s orbital (h). The large orange atom is Nd, the gray atom is Ni, and the small red atom is O.
