Electronic Structure of Neutral and Anionic Scandium Disilicon ScSi2–/0 Clusters and the Related Anion Photoelectron Spectrum

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• 作者：Le Nhan Pham ; Minh Tho Nguyen
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：December 1, 2016
• 年：2016
• 卷：120
• 期：47
• 页码：9401-9410
• 全文大小：403K
• ISSN：1520-5215

文摘

Several quantum chemical methods including DFT (B3LYP, BP86 functional), coupled-cluster theory (RCCSD(T)), and complete active space multiconfigurational methods (CASSCF/CASPT2) were used to study the geometric and electronic structures of the scandium disilicon cluster in both neutral and anionic states, ScSi₂^–/0. On the basis of the computed ground and lower-lying electronic states, and ionization energies of the anion, all the experimental bands in the anion photoelectron spectrum of ScSi₂^– can now fully be elucidated. The ³B₂ and ²B₂ states are determined to be the ground states of the anionic and the neutral triatomic species, respectively. The transition ³B₂ → ²B₂ is thus assigned to be responsible for the X band in the photoelectron spectrum. The ²A₁ neutral state is the final state corresponding to the A band. Although the first two bands arise from ionizations of scandium’s 4s and 3d orbitals, all three remaining bands with higher ionization energies are the results of one-electron removals from the Si₂ moiety orbitals of the anionic ground state ³B₂. Two electronic states of the same representations 1⁴B₂ and 2⁴B₂ are ascribed to be the carriers of the B and C bands, whereas the excited state ⁴A₂ is attributed to the last band D of the experimental photoelectron spectrum of ScSi₂^–. From all accessible vibrations of the ground and excited states computed at the B3LYP level, a simulation of band progressions in the photoelectron spectrum was also carried out and used to provide more insights into the experimental bands.