Metallic and superconducting gallane under high pressure

Using our newly developed particle swarm optimization algorithm on crystal structural prediction, we characterized the pressure-induced structural transition sequence of gallane (GaH3). As has been observed in alane (AlH3), enthalpy calculations reveal that the Pm (3) over barn structure of GaH3 becomes stable above 160 GPa, below which it is unstable with respect to elemental decomposition. Interestingly, the Pm (3) over barn structure is metallic, and the application of the Allen-Dynes modified McMillan equation reveals a high superconducting transition temperature (T-c), which reaches 86 K at 160 GPa and increases with decreasing pressure (T-c = 102 K at 120 GPa). Our band structure calculations demonstrate that GaH3 within the Pm (3) over barn structure is a highly ionic solid, where the ionicity of H atoms plays an important role in the predicted high temperature superconductivity.