First-principles studies of the structural, electronic, and optical properties of a novel thorium compound Rb2Th7Se15

The structural, electronic, and optical properties of a recently synthesized thorium compound Rb2Th7Se15 have been calculated in the density functional theory framework for the first time. The calculated direct band gap was 1.471 eV (generalized gradient approximation) and 1.171 eV (local density approximation), with both results being close to the experimental result of 1.83 eV. High covalency/iconicity of the Th-Se/Rb-Se bonds was demonstrated by calculating effective Mulliken charges of all ions. The polarized calculations of the complex dielectric function are presented; dependence of the calculated index of refraction was fitted to the Sellmeyer equation in the wavelength range from 500 to 2500 nm.