Crystal Structure and Phase Transition of XeF$_{2}$ at High pressures

We have investigated the crystal structure and phase transition of solid XeF$_{2}$ up to 51 GPa in diamond anvil cells by using Raman and synchrotron x-ray diffraction. The x-ray data indicates the tetragonal-to-orthorhombic phase transition at 7 GPa, which accompanies a small distortion ($<$ 1{\%}) in the ab-plane of the tetragonal structure. The Rietveld refinement further indicates a rapid change of intermolecular F...F contact distance with increasing pressures and, thereby, a rotation of linear symmetric XeF$_{2}$ molecules along the c-axis and the observed distortion in the ab-plane. This symmetry lowering tetragonal-to-orthorhombic transition also induces the Davydov splitting of symmetric stretching $\nu _{1}$ and bending $\nu _{2}$ modes in the Raman spectrum.