Optical properties of PuO2 and α-Pu2O3 by GGA + U + QA studies

By performing first-principles calculations plus quasi-annealing simulations, we systematically study the ground-state electronic and optical properties for PuO2 and α-Pu2O3. We find that α-Pu2O3 has an energy band gap of 1.38 eV. Our obtained atomic and electronic structures for the two plutonium oxides are in agreement with available experimental as well as other theoretical results. Based on the ground-state electronic structures, we systematically calculate the frequency dependent dielectric functions, as well as the optical spectra for α-Pu2O3 and PuO2. It is found that at the visible light frequency range, the adsorption coefficient of α-Pu2O3 and PuO2 are similar, but their refractive indexes differ much. This difference can be used to detect or trace the oxidation products of the plutonium surfaces.