Antishielding of Nuclear Quadrupole Moments in Heavy Ions

Sternheimer antishielding factors, γ_∞, are calculated for a number of heavy ions (K⁺, Ga⁺⁺⁺, Cl^-, Cu⁺, Rb⁺, Cs⁺, Br^-, and I^-), by using a variational procedure. Since there is more than one p shell and sometimes more than one d shell for these ions, an important modification of the original variational procedure was needed before it could be extended to these heavier ones. In the case of Cl^-, Rb⁺, and Cs⁺, we were able to compare our values with those obtained earlier by Sternheimer. We found a good agreement for Cl^-, but our values for Rb⁺ and Cs⁺ were somewhat lower. The reason for this discrepancy is discussed, and we conclude that for heavy ions, Sternheimer's procedure is more accurate than the variational procedure.The calculated values of γ_∞ are used to interpret two sets of data: (1) nuclear quadrupole coupling constants in a number of ionic diatomic molecules and ionic crystals; and (2) relaxation times in nuclear magnetic resonance experiments in some ionic crystals.