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Zamani AY, Hratchian HP. Assessing the performance of ΔSCF and the diagonal second-order self-energy approximation for calculating vertical core excitation energies. J Chem Phys 2022; 157:084115. [DOI: 10.1063/5.0100638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vertical core excitation energies are obtained using a combination of the ΔSCF method and the diagonal second-order (D2) self-energy approximation. These methods are applied to a set of neutral molecules and their anionic forms. An assessment of the results with the inclusion of relativistic effects is presented. For core excitations involving delocalized symmetry orbitals, the applied composite method improves upon the overestimation of ΔSCF by providing approximate values close to experimental K-shell transition energies. The importance of both correlation and relaxation contributions to the vertical core-excited state energies, the concept of local and non-local core orbitals, and the consequences of breaking symmetry are discussed.
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Affiliation(s)
| | - Hrant Patrick Hratchian
- Department of Chemistry & Biochemistry, University of California Merced, United States of America
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