The nature of the chemical bond in UO<inf>2</inf>
International Journal of Quantum Chemistry
John Wiley & Sons Inc.
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Maslakov, K., Teterin, Y., Ryzhkov, M., Popel, A., Teterin, A., Ivanov, K., Kalmykov, S., et al. (2019). The nature of the chemical bond in UO<inf>2</inf>. International Journal of Quantum Chemistry, 119 (24)https://doi.org/10.1002/qua.26040
The nature of the chemical bond in UO2 was analyzed taking into account the XPS structure parameters of the valence and core electrons, as well as the relativistic discrete variation (RDV) electronic structure calculation results for this oxide. The ionic/covalent nature of the chemical bond was determined for the UO8 (D4h) cluster, reflecting uranium’s close environment in UO2, and the U13O56 and U63O216 clusters, reflecting the bulk of solid uranium dioxide. The bar graph of the theoretical valence band (from 0 to ~35 eV) of XPS spectrum was built such that it was in satisfactory agreement with the experimental spectrum of a UO2 single crystalline thin film. It was shown that unlike the crystal field theory results, the covalence effects in UO2 are significant due to the strong overlap of the U 6p and U 5f atomic orbitals with the ligand orbitals, in addition to the U 6d AO. A quantitative MO scheme for UO2 was built. The contribution of the MO electrons to the chemical bond covalence component was evaluated on the basis of the bond population values. It was found that the IVMO electrons weaken the chemical bond formed by the OVMO electrons by 32% in UO8 and by 25% in U63O216.
The work was supported by the RFBR grant #17-03-00277a. M.V. Ryzhkov acknowledges the support of research provided by the state assignment for the Institute of Solid State Chemistry of the Ural Brunch of RAS No AAAA-A16-116122810214-9. The authors acknowledge support from Lomonosov Moscow State University Program of Development for providing access to the XPS facility.
External DOI: https://doi.org/10.1002/qua.26040
This record's URL: https://www.repository.cam.ac.uk/handle/1810/295513
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