CALCULATION OF SPIN-SPIN COUPLING-CONSTANTS USING DENSITY-FUNCTIONAL THEORY

A density functional method for the calculation of spin-spin coupling constants has been developed and applied to a large set of molecules. The results for the Fermi contact contribution are strongly dependent on the exchange-correlation functional. The results for proton-proton, carbon-proton, and carbon-carbon coupling constants are in good agree ment with experiment but the agreement worsens from N to F. Improved r esults for the Fermi contact contribution will require new functionals . Nevertheless, even at the current stage, the new method represents a powerful tool for the calculation of coupling constants in large orga nic and biological molecules.