Modified perturbation-variation method for calculating spin-spin coupling constants

Fermi contact nuclear spin-spin coupling constants are calculated by a perturbation-variation method. The trial function used includes a singularity at the nucleus and a variational term. Application to the HD molecule was carried out with an LCAO MO wavefunction expanded over a minimal Slater basis set. Using reasonable values of atomic orbital exponents α the calculated values bracket the experimental value of J_HD.