A CNDO calculation of nuclear spin-spin coupling constants in hydrocarbons

Abstract

The nuclear spin-spin coupling constants in methane, cthane, ethylene and acetylene are calculated using the Ramsey perturbation formalism. SCF MO's determined by the CNDO method are used to construct the ground state and all singly-excited triplet states. The coupling constants with and without configuration interaction between the triplet states are compared with independent electron calculations, full SCF calculations and experiment. The results show considerable improvement over those obtained by independent electron methods and are in reasonable agreement with experiment and the full SCF calculations.