摘要 : Anharmonic infrared spectra of 1,3-cyclopentadiene and its hexadeuterated isotopomer, 1,3-cyclopentadiene-d(6), have been calculated by means of second-order perturbation theory using Moller-Plesset second-order perturbation and d... 展开 Anharmonic infrared spectra of 1,3-cyclopentadiene and its hexadeuterated isotopomer, 1,3-cyclopentadiene-d(6), have been calculated by means of second-order perturbation theory using Moller-Plesset second-order perturbation and density functional theory (B3LYP and B97-1) methods with correlation consistent Dunning's basis sets (cc-pVDZ and cc-pVTZ). Computed anharmonic frequencies of fundamental, overtone and combination transitions are in satisfactory agreement with available experimental data. With exception of low-frequency ring torsion vibrations, introduction of the anharmonic corrections reduces the harmonic wavenumbers. The largest anharmonic effects are found for C-H and CH2 stretches, which decrease the harmonic frequencies by 100-130 cm(-1) (3-4%) and 140-160 cm(-1) (5-6%), respectively, reproducing the observed values within ca. 1%. For the antisymmetric CH2 stretching mode, the most significant anharmonic corrections are given by the diagonal and coupling with the symmetric CH2 vibration terms, together contributing to about 80% of the total anharmonic adjustment. Anharmonic calculations are important for a reliable prediction of the H/D isotopic frequency shift involving the C-H and CH2 stretching vibrations. (C) 2006 Elsevier B.V. All rights reserved. 收起