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Revisiting Mulliken’s Concepts about Rydberg States and Rydberg−Valence Interactions from Large-Scale Ab Initio Calculations on the Acetylene Molecule

2009; American Chemical Society; Volume: 113; Issue: 47 Linguagem: Inglês

10.1021/jp903948k

1520-5215

Fabrice Laruelle, Séverine Boyé-Péronne, D. Gauyacq, Jacques Liévin,

Catalysis and Oxidation Reactions

A quantitative characterization of the Rydberg and valence singlet electronic states of acetylene lying in the 5−10.7 eV region is performed by using large-scale ab initio calculations. A special attention is paid on the comparison between the present calculations and Mulliken's concepts for Rydberg states, based on single-electron and single-configuration description. Most of the properties of the Rydberg states have been qualitatively understood via this comparison, mainly shown by the shape and size of the outer Rydberg molecular orbital. More quantitatively, Rydberg−valence mixing has been evaluated in several excited energy regions, as for instance, the interaction between the C̃′ (1πg)2 1Ag doubly excited valence state and the manifold of electronic components of the np series, or the interaction between the Ẽ 1πg 1Bu valence state and the F̃ 3dπg 1Σu+ Rydberg state. The rapid predissociation of the lowest C̃ 3sσ 1Πu Rydberg state has been interpreted as a case of Rydbergization, earlier predicted by Mulliken.