First-principles study of the electronic structure and optical properties of cubic Perovskite NaMgF3

The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopotential density functional theory. The calculated lattice constant a(0), bulk modulus B-0, and the derivative of bulk modulus B-0' are 3.872 angstrom, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theoretical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of E-g = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV.