FP-LAPW study of the fundamental properties of the cubic spinel CdAl2O4

We have investigated the structural, elastic, electronic, optical and thermodynamic properties of the cubic spinel CdAl2O4 using accurate ab initio calculations. Computed equilibrium structural parameters are in good agreement with the available experimental data. Single-crystals elastic parameters are calculated for pressure up to 30 GPa using a conserving-volume total energy-strain method. Isotropic elastic parameters for ideal polycrystalline CdAl2O4 aggregates are computed in the framework of the Voigt–Reuss–Hill approximation. Result for band structure using the Engel–Vosko scheme of the GGA shows a significant improvement over the common GGA functionals. Optical spectra have been calculated for the energy range 0–30 eV. The peaks and structures in the optical spectra are assigned to interband transitions. Pressure dependence of the band gaps, static dielectric constant and static refractive index are also investigated. Pressure and thermal effects on some macroscopic properties are predicted using the quasi-harmonic Debye model.