Phase transition, elastic, and thermodynamic properties of NaF under high pressure

The phase transition and elastic properties of NaF are investigated by first-principle plane-wave pseudopotential density function theory method, and the thermodynamic properties are also obtained through the quasi-harmonic Debye model. The pressure of about 28 GPa for the phase transition of NaF from the rocksalt (B1) to the cesium chloride (B2) is obtained, which agrees better with the experimental data than previous theoretical results. The elastic constants C-11 and C-12 are found to monotonically increase with pressure; however, C-44 is almost constant with pressure, which agrees well with the experimental results. The dependences of both the relative volume on the pressure and the heat capacity on the temperature and pressure are also investigated.