First-principles calculations of structural, electronic and optical properties of tetragonal SnO2 and SnO

The structural, electronic and optical properties of tetragonal SnO2 and SnO were investigated by the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The calculated structural parameters are in good agreement with previous calculation and experimental data. The energy band structures, density of states and charge densities are calculated and analyzed. The calculated carrier effective masses are shown to be anisotropic. Furthermore, in order to understand the optical properties of tetragonal SnO2 and SnO, the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption efficient, loss function and complex conductivity function are calculated for radiation up to 40 eV. We have explained the origin of the spectral peaks on the basis of the theoretics about crystal-field and molecular-orbital bonding.