Nuclear hexadecapole antishielding factors

Using Hartree-Fock-Slater wave functions, values of the nuclear hexadecapole antishielding factor η_∞ have been calculated for the following ions: Ti³⁺, Mn²⁺, Cu⁺, Zn²⁺, Ge⁴⁺, Rb⁺, Zr³⁺, Nb⁵⁺, Tc²⁺, Ag⁺, In³⁺, Sb³⁺, Cs⁺, Hf³⁺, Re²⁺, Au⁺, Hg²⁺, Bi³⁺, Fr⁺, Th³⁺, and Am²⁺. The radial distortions induced in the core electrons due to nuclear hexadecapole moment were calculated using Sternheimer's perturbation numerical procedure. The contribution to η_∞ due to the nf shell is much weaker in magnitude than that from the nd shell. In the three nd series of ions considered here, maximum values of η_∞ are obtained in the cases of Cu⁺, Ag⁺, and Au⁺ ions, respectively, where the outer d shell is complete and is most external. With the assumption that a large nuclear quadrupole moment may be associated with a significant hexadecapole moment, it is suggested that of the systems examined here containing nuclei with spin I≥2, Bi³⁺, Re²⁺, Sb³⁺, In³⁺, and Mn²⁺ are likely to exhibit prominently nuclear hexadecapole interaction effects since these have favorable natural abundance, quadrupole moment, magnetic resonance sensitivity, and large η_∞ values.