Ab initio study of germanium-hydride compounds under high pressure

Motivated by the potential high-temperature superconductivity in hydrogen-rich materials and phase transitions, germanium-hydride compounds under high pressure were studied by a genetic algorithm. Enthalpy calculations suggest that the Ge and H will form Ge3H, Ge2H, GeH3, and GeH4 at about 32, 120, 280, and 280 GPa, respectively. These four germanium-hydride compounds are all stable up to at least 300 GPa. For Ge3H, the most stable structure is P-Ge3H at 32–220 GPa and P63/m-Ge3H at 220–300 GPa. All the germanium-hydride compounds are metallic phases as demonstrated by the band structure and density of states.