Ab initio and DFT calculations of structure and vibrational spectra of pyridine and its isotopomers

The molecular parameters and vibrational spectra of pyridine, pyridine-d(5) and partially deuterated pyridines have been computed using the MP2, BLYP, BP86, BVWN, SVWN and B3LYP methodology and the cc-pVDZ, cc-pVTZ and 6-311 + + G(d,p) basis sets. The results are compared with the available experime ntal data in the gas phase. Bond distances, bond angles, dipole moment and harmonic frequencies computed by the MP2/cc-pVTZ and B3LYP/cc-pVTZ are in g ood agreement with the available experimental data. The calculations are fo und to be valuable in verifying a number of less certain experimental vibra tional assignments. The results suggest that the DFT methods incorporate so me anharmonic contributions, which improve the agreement with the experimen tal frequencies. (C) 2001 Elsevier Science B.V. All rights reserved.