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

✍ Scribed by Ming-Xing Song; Zeng-Xia Zhao; Wei Zhang; Fu-Quan Bai; Hong-Xing Zhang; Chia-Chung Sun

• Publisher: Elsevier
• Year: 2011
• Tongue: English
• Weight: 327 KB
• Volume: 964
• Category: Article
• ISSN: 2210-271X
• DOI: 10.1016/j.comptc.2011.01.005

✦ Synopsis

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-Teller effect on the CCCF radical, C s symmetry was used for CCCF. The CCCF has been found to have a X 2 A 0 ground state with rotational constant B = 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 2 A 0 ? 3 2 A 00 and X 2 A 0 ? 5 2 A 0 , 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 2 A 0 of CCCX can be described as allenic structures with the unpaired electron on the C3 atom, while the excited state 1 2 A 00 (1 2 P) of CCCX have the linear acetylenic structures with the unpaired electron on the C1 atom. The barriers to linearity decrease as follows: DE (CCCF) < DE (CCCCl) < DE (CCCBr).