Study of relativistic effects on nuclear shieldings using density-functional theory and spin-orbit pseudopotentials

We combine a perturbational calculation, using spin-orbit pseudopotentials, of the spin-orbit effect on nuclear shieldings with scalar relativistic ef fects taken into account self-consistently using quasirelativistic pseudopo tentials. The shieldings are calculated for light nuclei in systems contain ing heavy atoms, for which matching spin-orbit and quasirelativistic pseudo potentials are used. The second-order spin-orbit contribution arising from the magnetic field dependence of the one-electron spin-orbit Hamiltonian is -also included. The method is implemented within the framework of density-f unctional theory and is capable of treating large molecular systems economi cally. Calculations are presented for the HX and CH3X (X = F, Cl, Br, I) mo lecules, third-row transition metal carbonyls, and a series of methyl mercu ry compounds. (C) 2001 American Institute of Physics.