Main and Satellite Features in the Ni 2p XPS of NiO
| Autor: | Paul S. Bagus, Connie J. Nelin, C. Richard. Brundle, B. Vincent Crist, Eugene S. Ilton, Nabajit Lahiri, Kevin M. Rosso |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Inorganic Chemistry. 61:18077-18094 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | The origin and assignment of the complex main and satellite X-ray photoelectron spectroscopy (XPS) features of the cations in ionic compounds have been the subject of extensive theoretical studies using different methods. There is agreement that within a molecular orbital model, one needs to take into account different types of configurations. Specifically, those where a core electron is removed, but no other configuration changes are made and those where in addition to ionization, there are also shake or charge-transfer changes to the ionic configuration. However, there are strong disagreements about the assignment of XPS features to these configurations. The present work is directed toward resolving the origin of main and satellite features for the Ni 2p XPS of NiO based on ab initio molecular orbital wave functions (WFs) for a cluster model of NiO. A major problem in earlier ab initio XPS studies of ionic compounds has been the use of a common set of orbitals that was not able to properly describe all the ionic configurations that contribute to the full XPS spectra. This is resolved in the present work by using orbitals that are optimized for averages of the occupations of the different configurations that contribute to the XPS. The approach of using state-averaged (SA) orbitals is validated through comparisons between different averages and through use of higher order excitations in the WFs for the ionic states. It represents a major extension of our earlier work on the main and satellite features of the Fe 2p XPS of Fe |
| Databáze: | OpenAIRE |
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