RELATIVISTIC THEORY FOR INDIRECT NUCLEAR-SPIN SPIN COUPLINGS WITHIN THE POLARIZATION PROPAGATOR APPROACH

We present a relativistic theory for the nuclear spin-spin coupling te nsor within the polarization propagator approach using the particle-ho le Dirac-Coulomb-Breit Hamiltonian and the full four-component wave fu nction. We give explicit expressions for the coupling tensor in the ra ndom-phase approximation, neglecting the Breit interaction. A purely r elativistic perturbative electron-nuclear Hamiltonian is used and it i s shown how the single relativistic contribution to the coupling tenso r reduces to Ramsey's three second-order terms (Fermi contact, spin-di pole, and paramagnetic spin-orbit) in the nonrelativistic limit. The p rincipal propagator becomes complex and the leading property integrals mix atomic orbitals of different parity. The well-known propagator ex pressions for the coupling tensor in the nonrelativistic limit is obta ined neglecting terms of the order c(-n) (n greater-than-or-equal-to 1 ). (C) 1993 John Wiley & Sons, Inc.