Exchange Core-Polarization Effects on Indirect Nuclear Spin Interactions-Application to Rubidium and Cesium Metals

The role of exchange core-polarization (ECP) effects in the study of indirect nuclear spin interactions (INSI) in the alkali metals rubidium and cesium is discussed. The ECP contributions to the INSI parameters $A_{12}$ (Ruderman-Kittel) and $B_{12}$ (pseudodipolar) are evaluated and compared with other contributions. The theoretical values of $A_{12}$ are in reasonable agreement with experiment. However, the incorporation of the ECP contributions to $B_{12}$, ${\left(B_{12}\right)}_{\mathrm{ECP}}^{\mathrm{dip}}$ (in this ECP process, the conduction electrons are polarized by the electron-nuclear dipolar interaction, and the exchanged polarized core electrons interact with the nucleus via the Fermi contact interaction) does not improve the order-of-magnitude disagreement between theory and experiment. The importance of additional ECP processes whose inclusion can improve the theoretical situation is briefly discussed.