Since the discovery of superconductivity in infinite-layer nickelates, extensive research has been devoted to uncovering the underlying mechanisms of this phenomenon. Here, combining density functional theory and Wannier function calculations, we show that increasing the interlayer spacing of Nd-${\mathrm{NiO}}_2$ enhances the Ni $e_g$ orbital polarization and effective Ni $d_{x^2-y^2}$ nearest-neighboring hopping while suppressing the hybridization between Ni $d_{x^2-y^2}$ and interstitial $s$ orbitals. The pronounced two-dimensional character of the electronic structure and resultant conduction pathways may be favorable for superconductivity. Furthermore, the interlayer spacing strongly affects Fermi surface topology and pocket size around the A point in the first Brillouin zone, i.e., the self-doping effect. Given that the self-doping effect is considered a key feature distinguishing nickelates from cuprates, this may help explain why the superconducting transition temperature of cuprates is higher. Our results highlight the critical role of interlayer spacing in tuning the electronic structure of infinite-layer nickelates and suggest a feasible route to optimizing superconductivity through structural engineering.

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• Density of states
• Electronic structure
• Fermi surface
• Nickelates
• Superconductors
• Density functional theory
• First-principles calculations
• Wannier function methods