Calculation of nuclear spin-spin coupling constants with ab initio molecular orbital wave functions

Abstract

We investigate the use of ab initio molecular wave functions to evaluate the Fermi contact contribution to nuclear spin-spin coupling constants n J AB (A, B=C, H) for a data set of 19 molecules having well-defined experimental geometry and coupling values. We critically examine the theoretical and numerical problems associated with the Dirac δ function operator and its perturbation-theoretic treatment. We show that the common approximation of neglecting basis orbitals not centered on the coupled nuclei is a major source of error in previous calculations