Calculation of the Electronic Structure of AmO2 and Pr6O11 for XANES Analysis With Redox Property

摘要

We calculated X-ray absorption near-edge structure (XANES) of Am L-III of AmO2 and Pr L-III of Pr6O11 using the relativistic discrete-variational (DV)-X alpha method based on the Dirac-Slater method, and compared it with the experimental spectra. These spectra were calculated on a model of AmO2 ([AmO8](12-)) and Pr6O11 ([PrO8](12-)). In spite of using small cluster models, the calculated spectra were in good agreement with the experiment ones. Besides, we calculated the electronic structure of AmO2 and Pr6O11 to analyze the peak structures of XANES. From this calculation, it was found that O s, p, and f components had influence on the specific peak structures but that O d component had influence on various peak structures for AmO2 and Pr6O11. From this result, it was suggested that the change of the electronic structure of actinide 6d and O d or f was important for actinide L-III XANES corresponding to oxygen to metal ratio in the oxide nuclear fuel. On the basis of these results, we calculated the fine structures of densities of states and the transition energy from the HOMO to the white line of AmO2, UO2, and Pr6O11 and investigated redox properties of Am and U in the oxide nuclear fuel with the evaluation of validity of Pr as simulant materials of Am.