The harmonic force field for the out-of-plane vibrations of pyridine has been calculated from ab initio Hartree-Fock wavefunctions obtained with a 4-21 basis set of contracted Gaussians. To account for systematic errors, the calculated force constants were scaled, using only two independent sclae factors which were transferred unchanged from benzene. The resulting scaled quantum mechanical force field, which is strictly a priori in that it is not based on any experimental data on pyridine, predicts the 64 out-of-plane fundamental frequencies of pyridine and its deuterated isotopomers of C2v symmetry with a mean deviation from experiment of only 8.5 cm-1. Addition of polarization functions to the basis set for the nitrogen atom and refinement of the two scale factors by fitting them to the observed pyridine spectra produce no significant improvement in the fit. Assignments of the vibrational spectra are discussed.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry