The structural and thermodynamic properties of CaLi2 at high pressure

In this work, the structural, mechanical and thermodynamic properties of CaLi2 in the pressure range of 0-72GPa have been studied. It was found that CaLi2 undergoes a phase transition from P63/mmc to C2/c phase at 25.37GPa and from C2/c to P21/c phase at 55.99GPa, which is consistent with previous experimental and partially theoretical results. Besides, at 0GPa, the lowest enthalpy appears in both P63/mmc and Fd-3m structures, showing the coexistence of these two phases. However, P63/mmc phase is not stable when the pressure is larger than 6GPa. Finally, the elastic of CaLi2 at different pressures was investigated using the elastic stability criterion, and the thermodynamic properties under different pressures are investigated in detail.