BASIS-SET DEPENDENCE OF MAGNETIC SHIELDING CONSTANT CALCULATED BY THEHARTREE-FOCK FINITE PERTURBATION METHOD

We investigate the basis set dependence and the gauge origin dependenc e in the calculations of Se and Cd nuclear magnetic shielding constant s of several selenium and cadmium compounds. We improve the basis set systematically by adding the first-order higher angular momentum basis functions (FOBFs) to the conventional basis sets, as proposed previou sly, in the ab initio Hartee-Fock/finite perturbation method. The calc ulated results become almost independent on the employed basis sets wh en this improvement is done. Furthermore, it is shown that the mechani sms of the chemical shifts are basis-set independent. The dominances o f the p-hole mechanism in the Se chemical shift and the p-electron mec hanism in the Cd chemical shift are valid for all the basis set examin ed in this paper.