Employing first-principles density functional theory calculations and Wannierization of the low-energy band structure, we analyze the electronic structure of undoped, infinite-layer nickelate compounds ${\mathrm{NdNiO}}_2,$ ${\mathrm{PrNiO}}_2,$ and ${\mathrm{LaNiO}}_2$. Our study reveals the important role of the nonzero $f$-ness of Nd and Pr atoms, as opposed to the $f^0$ occupancy of La. The nonzero $f$-ness becomes effective in lowering the energy of the rare-earth $5d$ hybridized axial orbital, thereby enhancing the electron pockets and influencing the Fermi surface topology. The Fermi surface topology of ${\mathrm{NdNiO}}_2$ and ${\mathrm{PrNiO}}_2$ is strikingly similar, while differences are observed for ${\mathrm{LaNiO}}_2$. This difference shows up in computed doping-dependent superconducting properties of the three compounds within a weak coupling theory, which finds two-gap superconductivity for ${\mathrm{NdNiO}}_2$ and ${\mathrm{PrNiO}}_2$, and the possibility of a single-gap superconductivity for ${\mathrm{LaNiO}}_2$ with the strength of superconductivity suppressed by almost a factor of 2, compared to the Nd or Pr compound.

• Received 28 September 2020
• Revised 17 November 2020
• Accepted 17 November 2020

DOI:https://doi.org/10.1103/PhysRevB.102.220502