On a Perturbed Hartree-Fock Study of the Magnetic Susceptibility and the 13C and 17O NMR Shielding Constants in Formaldehyde with Slater Basis Sets

The theoretical study of Flygare et al. on one-electron properties of the formaldehyde molecule is extended to include the paramagnetic susceptibility and the 13C and 17O NMR shielding constants and to investigate their sensitivity to Slater basis-set quality. The Gaussian transform method is used to evaluate the necessary integrals. Using the fully coupled perturbed Hartree-Fock formalism, we find that improvements in the wavefunction produce significant changes in most components of the second-order properties. The best shielding calculations, obtained with a double-zeta Slater set, are within the rather large experimental uncertainties, whereas the agreement between the theoretical and experimental susceptibility results is less satisfactory. The complete paramagnetic tensors are analyzed in terms of MO and AO contributions. Comparisons are made with other ab initio calculations and with simplified forms of the theory.