Formation of ammonia–helium compounds at high pressure

摘要

Calculated enthalpies of formation (Δ ) of various NH –He compounds with respect to decomposition into solid NH and He at selected pressures. Convex hulls are shown as solid lines with (blue) and without (magenta) the inclusion of zero-point vibrational energies. Calculations adopted the 2 /3 structure at 10 GPa, the 2 2 2 phase at 50 GPa, and the 2 structure at 100, 150, and 300 GPa for NH  and -He at all pressures.