View article

Superconducting nickelates appear to be difficult to synthesize. Since the chemical reduction of [rare earth (), transition metal ()] with may result in both and , we calculate the topotactic H binding energy by density functional theory (DFT). We find intercalating H to be energetically favorable for but not for Sr-doped . This has dramatic consequences for the electronic structure as determined by mean field theory: that of is similar to (doped) cuprates, is a two-orbital Mott insulator. Topotactic H might hence explain why some nickelates are superconducting and others are not.