Finite perturbation configuration interaction calculations of nuclear spin-spin coupling constants

Non-empirical finite perturbation calculations at the Hartree-Fock and configuration interaction levels of approximation are reported for the vicinal proton-proton coupling constant in ethane for different values of the dihedral HCCH' angle. The correlation effects are found to be of importance. The results fit the Karplus relation well. The calculated values are in good agreement with available experimental data when the correlation contribution is included. Possibilities of using approximation in evaluating the correlation energy are discussed. (orig.)