Sternheimer Shielding-Antishielding; Rare-Earth Ions

Sternheimer shielding-antishielding parameters pertinent to the quadrupole perturbations outside an ion (), as well as within the ion owing to an unfilled 4f shell (R), have been calculated for rare-earth ions La^3+, Ce^3+, Pr^3+, Nd^3+, Pm^3+, Sm^3+, Eu^3+, Gd^3+, Tb^3+, Dy^3+, Ho^3+, Er^3+, Tm^3+, Yb^3+, Lu^3+, Sm^2+, and Eu^2+. Hartree---Fock---Slater-type ionic wave functions have been used. The value of ₀ varies smoothly from -65. 82 for La^3+ to -58. 49 for Yb^3+, whereas that of R₀ (without exchange) varies from 0. 081 for Ce^3+ to 0. 128 for Yb^3+. The calculation of Sternheimer parameters for Sm^2+ and Eu^2+ with ₀=-73. 28 and R₀=0. 124 for Sm^2+ shows that their dependence on the charge of the ions is appreciable. Sternheimer parameters are reported also for the core-electron sites.