Stability and superconducting properties of GaH5 at high pressure

Using genetic algorithm (GA) method combined with first-principles calculations, the structures, dynamical and thermodynamic stabilities of GaH5 were studied. The calculated results suggested that at the pressure range 150-400 GPa, the P21/m phase of GaH5 is the most favorable phase and dynamically stable, but thermodynamically it is unstable and can decompose into GaH3 and H2. The superconducting property of GaH5 was further calculated, and the predicted superconducting transformation temperature Tc of GaH5 P21/m phase is about 35.63 K at 250 GPa. Besides, we compared the GaH5 and GaH3 superconducting properties, and found that GaH3-Pm-3n structure has a larger DOS near Fermi level than GaH5-P21/m structure, which may be the main reason causing higher Tc of GaH3 than GaH5.