First-principles study on the electronic and optical properties of BiFeO3

The structural, electronic, and optical properties of multiferroic bismuth ferrite (BiFeO3) are investigated using density functional theory within generalized gradient approximation (GGA). The calculated lattice parameters are in good agreement with the experimental data. The electronic structure shows that BiFeO3 has an indirect (very close to direct) band gap of 1.06 eV. The complex dielectric function, absorption spectra, refractive index, extinction coefficient, energy-loss spectrum and reflectivity are calculated, and the results are compared with the available experimental data. Finally, the optical properties of BiFeO3 are discussed based on the band structure calculations.