Absence of electron-phonon-mediated superconductivity in hydrogen-intercalated nickelates

A recent experiment [X. Ding et al., Nature (London) 615, 50 (2023)] indicates that superconductivity in nickelates is restricted to a narrow window of hydrogen concentration, 0.22 < x < 0.28 in Nd0.8Sr0.2NiO2Hx. This reported necessity of hydrogen suggests that it plays a crucial role for superconductivity, as it does in the vast field of hydride superconductors. Using density-functional theory and its extensions, we explore the effect of topotactic hydrogen on the electronic structure and phonon-mediated superconductivity in nickelate superconductors. Our calculations show that the electron-phonon coupling in hydrogen-intercalated nickelates is not strong enough to drive the electron pairing, and thus cannot explain the reported superconductivity.