Ab initio investigation of lattice dynamics of fluoride scheelite LiYF4
  We report on the phonon dynamics of LiYF4 obtained by direct method using first principle calculations. The agreement between experimental and calculated modes is satisfactory. An inversion between two Raman active modes is noticed compared to inelastic neutron scattering and Raman measurements. The atomic displacements corresponding to these modes are discussed. Multiple inversions between Raman and infrared active groups are present above 360 cm-1. The total and partial phonon density of state is also calculated and analyzed. 
Benoit Minisini (ISMANS), Qiuping A. Wang (ISMANS), Fran\c{c}ois   Tsobnang (ISMANS)