Rigid ion model of lattice dynamics in the laser host fluoroscheelites LiYF4 and LiYbF4 - art. no. 024304

We report in this paper a panoptic picture of the lattice dynamics for LiYF 4, on the basis of a rigid ion model. The resulting analysis yields the dis persion of phonon branches in accord with the measured experimental phonon dispersion curves along some of the most important symmetry directions as m easured by neutron inelastic scattering. The model is then extended for LiY bF4, using suitable parameters corresponding to Yb3+ ions. Our calculated r esults are found to comfortably match the experimental data on Raman as wel l as IR active phonons and also on various thermodynamic properties in both the crystals.