First-principles study of the electronic and optical properties in rhombohedral LaAlO3

In this paper, the electronic structure, chemical bonding, and optical properties of rhombohedral LaAlO3 are investigated by using the full potential linearized augmented plane wave method with the generalized gradient approximation. The analysis of the electronic density profile, Mulliken charge, and bond population shows a combination of the covalent and ionic natures in the chemical bonding. The calculated complex dielectric function is consistent with the experimental data from the ultraviolet spectroscopic ellipsometry measurement. The optical spectra are assigned to the interband transition from O valence to La conduction bands in the low energy region. Furthermore, absorption spectrum, electron energy-loss spectrum, optical conductivity, reflectivity, and refractive index are derived from the complex dielectric function; and the absorption spectrum exhibits an optical band gap of 6.1 eV, which is consistent with several other experimental measurements. (C) 2008 American Institute of Physics.