CONICET | Buscador de Institutos y Recursos Humanos

The structural, electronic and optical properties of the insulator alpha-AlF3 are investigated by rst principles calculationsusing density functional theory, and the band gap and optical response is measured. Our calculations use the generalizedgradient approximation for the exchange and correlation potential, within a pseudopotential scheme. In order to improvethe ground state formulation for the electronic and optical properties, we included many body eects through the GWapproximation for the band gap and the Bethe Salpeter equation for the excitonic eects in the optical calculations. Wecontrast our calculations with experiments, by combining Ultraviolet and X-ray Photoelectron spectroscopies on AlF3lms grown over Cu(100) to determine the electronic structure, and electron energy loss spectra (EELS) to comparethe optical spectra. The density of states shows the important role of F-p states in the bonding, and the bandstructure reveals the direct band gap at the Gamma point of the material, with a value of 10.81 eV obtained within the GWapproximation, in very good agreement with the experimental value of 10 eV. We also calculated the imaginary epsilon2(w)and real epsilon1(w) parts of the dielectric function, the refractive index, the extinction coecient, the reflectivity at normalincidence, and the electron energy loss spectrum which is in reasonable agreement with the experimental curve, obtainingthe main peak in the region about 25 eV. With the Bethe Salpeter equation we calculated the energy loss spectra of thelow energy region above the band gap, where we found excitonic eects that explain the observed experimental peakin this region.