Calculation of the Jahn-Teller effect in benzene cation: Application to spectral analysis

摘要

Ab initio calculations have been performed for the cations of benzene, C_6H_6, and its fluorinated analogs, C_6F_6 and C_6H_3F_3. Calculated molecular parameters characterizing the Jahn-Teller potential energy surface (PES) are very consistent with those derived from the spectra of C_6F_6~+ and C_6H_3F_3~+. However the calculated Jahn-Teller stabilization energy for the benzene cation is roughly three times greater than that previously reported experimentally. With the aid of th ecalculated values, a more complete analysis of the available spectral data for C_6H_6`+ and C6D_6~+ is performed, with an emphasis on the data from ZEKE experiments and IR spectra of the Ar centre dot C_6H_6~+, Ne centre dot C_6H_6~+, and Ar centre dot C_6D_6~+ complexes. The comprehensive analysis reveals Jahn-Teller activity in 3 e_2g modes for C_6(H/D)_6`+ and provides values for their vibrational frequencies, linear and quadratic Jahn-Teller coupling constants, as well as quadratic coupling constants for several other degenerate models. These new molecular parameters are generally in good agreement with the correspnding good agreement with the computed value.