Phonon density of states of metallic Sn at high pressure.

Determination of the lattice dynamics of Sn at high pressure has represented a major experimental challenge and eluded previous attempts. Here we report the first successful measurement of the phonon density of states of Sn at high pressure to 64 GPa using nuclear resonant inelastic x-ray scattering. We also present density functional theory calculations that are in excellent agreement with the measured data. The results of this combined experimental and theoretical study establish reliable phonon density of states of Sn at high pressure. It makes possible an accurate description of its thermodynamic properties that are of great importance and interest in high pressure research.