The structural, electronic and optical properties of two principal
representatives of spinel oxides CdGa2O4 and CdIn2O4
have been investigated using the full-potential augmented plane-wave plus
local orbitals method within density functional theory. We used the
generalized gradient approximation (GGA) for the exchange-correlation (XC)
potential. Moreover, the alternative form of GGA proposed by Engel and Vosko
(GGA-EV) is also used for the band structure calculations. The equilibrium
lattice constants and the internal parameters are in agreement with the
available experimental results. Results obtained for band structure using
GGA-EV show a significant improvement over other theoretical work and are
closer to the experimental data. The pressure dependence of band gaps is
investigated. The dielectric function, reflectivity spectra and refractive
index are calculated up to 50 eV. Pressure and volume dependence of the
static refractive index have been also calculated.