Sternheimer Shielding-Antishielding; Rare-Earth Ions

Sternheimer shielding-antishielding parameters pertinent to the quadrupole perturbations outside an ion (λ), as well as within the ion owing to an unfilled 4f shell (R), have been calculated for rare-earth ions La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Pm³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, Lu³⁺, Sm²⁺, and Eu²⁺. Hartree---Fock---Slater-type ionic wave functions have been used. The value of λ₀ varies smoothly from -65.82 for La³⁺ to -58.49 for Yb³⁺, whereas that of R₀ (without exchange) varies from 0.081 for Ce³⁺ to 0.128 for Yb³⁺. The calculation of Sternheimer parameters for Sm²⁺ and Eu²⁺ with λ₀=-73.28 and R₀=0.124 for Sm²⁺ shows that their dependence on the charge of the ions is appreciable. Sternheimer parameters are reported also for the core-electron sites.