Ab initio pressure-dependent vibrational and dielectric properties of ${\mathrm{CeO}}_2$

We have performed an ab initio study of pressure-dependent dielectric and lattice dynamical properties of ${\mathrm{CeO}}_2$. The calculations have been carried out within the local density functional approximation using norm-conserving pseudopotentials and a plane-wave basis. Born effective charge tensors, dielectric permittivity tensors, the phonon dispersion curves, and their Grüneisen parameters are calculated using density functional perturbation theory. The calculated results agree well with the experiments. Also, we have found that treating the $4f$ electrons of cerium as valence states is crucial for a satisfactory description of the lattice dynamical properties of ${\mathrm{CeO}}_2$.

Figure 1

Calculated phonon dispersions of ${\mathrm{CeO}}_2$ through high-symmetry points of Brillouin zone with neutron data (diamonds) of Ref. 16.

Figure 2

Calculated mode Grüneisen parameters of ${\mathrm{CeO}}_2$ through high-symmetry points of the Brillouin zone. Closed circles at the $\Gamma$ point are the experimental results of Ref. 15.