Theoretical study of the low-lying electronic states of CCCF radical and its ions

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• 作者：Ming-Xing  ; Song ; Zeng-Xia  ; Zhao ; Wei  ; Zhang ; Fu-Quan  ; Bai ; Hong-Xing  ; Zhang  ; ;   ; ^{zhanghx@mail.jlu.edu.cn} ; Chia-Chung  ; Sun
• 关键词：CCCF ; CASSCF ; Excited state ; Radidal
• 刊名：Computational and Theoretical Chemistry
• 出版年：2011
• 出版时间：March 2011
• 年：2011
• 卷：964
• 期：1-3
• 页码：277-282
• 全文大小：326 K

文摘

The low-lying electronic states of the CCCF radical and its ionic states have been investigated systematically using the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with aug-cc-pVTZ basis set. To investigated the Renner¨CTeller effect on the CCCF radical, mlns="""">C_s symmetry was used for CCCF. The CCCF has been found to have a X^mlns="""">2A?ground state with rotational constant = 4500.5 MHz, which is in good agreement with the experimental values of 4555.8043 MHz. The calculations of vertical excitation energies of CCCF at 2.893 and 4.180 eV are attribute to the X^mlns="""">2A??3^mlns="""">2A?and X^mlns="""">2A??5^mlns="""">2A? respectively, which has larger oscillator strengths. The ionization potentials of CCCF are computed in order to provide a theoretical guidance to the photoelectron spectrum (PES) of the CCCF radical. The first adiabatic electron affinity (AEA) of CCCF is predicted to be 2.671 eV. A comparison of the geometries and bonding among the CCCX (X = F, Cl, and Br) radicals presents the ground state X^mlns="""">2A?of CCCX can be described as allenic structures with the unpaired electron on the C3 atom, while the excited state 1^mlns="""">2A?(1^mlns="""">2¦°) of CCCX have the linear acetylenic structures with the unpaired electron on the C1 atom. The barriers to linearity decrease as follows: ¦¤mlns="""">E (CCCF) < ¦¤mlns="""">E (CCCCl) < ¦¤mlns="""">E (CCCBr).