A first-principles investigation of superconducting properties of AlCeH6

Abstract

Ternary hydrides are promising candidates for low-pressure hydrogen-rich superconductors. In this work, we investigate AlCeH6 using first-principles density functional theory, including both harmonic and anharmonic phonon calculations. The compound crystallizes in a rhombohedral R3¯m structure composed of corner-sharing [AlH6] octahedra that form an extended hydrogenic framework, with Ce atoms occupying interstitial sites between the octahedra. Electronic structure analysis reveals metallicity with Ce bands near the Fermi level, suggesting a multiband character. Phonon calculations indicate a low-frequency Ce mode stabilized by anharmonic effects, while high-frequency H modes remain largely unchanged. Electron–phonon coupling is dominated by hydrogen vibrations, contributing over 60% of the total λ. The estimated superconducting transition temperatures are Tc = 53−42 K in harmonic and 43–34 K in anharmonic corrections for μ* = 0.10−0.13, with BCS ratios close to the weak-coupling limit, indicating moderate coupling. These results demonstrate that AlCeH6 is a dynamically stable, hydrogen-rich superconductor at ambient pressure and highlight the potential of compositional tuning in ternary hydrides to achieve low-pressure superconductivity.