CASSCF/CASPT2 Calculation of the Low-Lying Electronic States of the CH3Se Neutral Radical and Its Cation

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• 作者：Ming-Xing Song ; Zeng-Xia Zhao ; Fu-Quan Bai ; Yue-Jie Liu ; Hong-Xing Zhang ; Chia-chung Sun
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：July 8, 2010
• 年：2010
• 卷：114
• 期：26
• 页码：7173-7178
• 全文大小：121K
• 年卷期：v.114,no.26(July 8, 2010)
• ISSN：1520-5215

文摘

Electronic states of the CH₃Se and its cation CH₃Se⁺ have been studied using the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with the ANO-RCC(TZP) basis set. To investigate the Jahn−Teller effect on the CH₃Se radical, C_s symmetry was used for CH₃Se in calculations. The results show that the Jahn−Teller effect is very small (69 cm⁻¹) and the 1²A′ state is slightly more stable than the 1²A′′ state (8 cm⁻¹). The CH₃Se has been found to have a 1²A′ ground state with a C−Se bond distance of 1.975 Å. The computed C−Se stretching ν₆(a′) frequency is 554.1 cm⁻¹, which is in good agreement with the experimental values of 600 ± 60 cm⁻¹. The calculations for CH₃Se at 3.621 and 5.307 eV are attributed to 1²A′ → 2²A′(1²A₁) and 1²A′ → 2²A′′, respectively. The vertical and adiabatic ionization energies were obtained to compare with the PES data.