Spin-orbit corrections to the indirect nuclear spin-spin coupling constants in XH(4) (X=C,Si,Ge, and Sn)

Using the quadratic response function at the ab initio SCF level of approximation we have calculated the relativistic corrections from the spin-orbit Hamiltonian, H-SO, to the indirect nuclear spin-spin coupling constants of XH(4) (X = C, Si, Ge, and Sn). We find that the spin-orbit contributions to J(X-H) are small, amounting only to about 1% for J(Sn-H). For the geminal H-H coupling constants the relativistic corrections are numerically smaller than for J(X-H), but in some cases relatively larger compared to the actual magnitude of J(H-H). We also investigate the use of an effective one-electron spin-orbit Hamiltonian rather than the full H-SO in the calculation of these corrections.