Variational calculation of lower vibrational energy levels of formaldehyde X̃ 1A1

Abstract

The energies of lower lying vibrational states (J=0) of formaldehyde in its ground electronic state are calculated variationally for H₂CO and D₂CO. The functions of the basis set correspond to products of harmonic oscillator functions. The full Watson Hamiltonian is used and integrals are evaluated by Gauss–Hermite numerical quadrature. Two different potential functions in internal displacement coordinates, which have been given in the literature, are employed in the calculations. Calculations are carried out for A₁, B₂, and B₁ symmetries with 196, 165, and 108 basis functions, respectively. The forms of some of the eigenvectors are reported.