Spin–orbit corrections to the indirect nuclear spin–spin coupling constants in XH4 (X=C, Si, Ge, and Sn)

Summary.  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 XH₄ (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. Received July 12, 1996 / Final revision received September 12, 1996 / Accepted September 17, 1996