Calculation of Spin–Orbit Coupling Constants and Other Radial Parameters for the Actinide Ions Using Relativistic Wavefunctions

Abstract

Relativistic self‐consistent Dirac–Slater and Dirac–Fock wavefunctions have been used to evaluate the spin–orbit coupling constant and matrix elements of $r^n$ for most of the actinide ions and neutral atoms. Empirical corrections for the Dirac–Slater ${\zeta }_{\text{5f}}$ constants based on experimental results are suggested which enable one to predict free‐ion values more accurately. Values of ${\zeta }_{\text{5f}}$ from crystal and solution spectra show reductions from these estimates which are independent of atomic number $Z$ , but vary roughly according to ionic charge and ligand electronegativity. It is shown that ${\mathrm{〈r}}^{\text{−3}}〉$ parameters from atomic beam measurements on Sm, Eu, Pu, and Am can be accounted for fairly well with relativistic Dirac–Slater wavefunctions and intermediate coupling eigenvectors; configuration interaction, core polarization, and other contributions to hyperfine coupling are neglected. Similar calculations with hyperfine coupling constants from crystal EPR spectra are less consistently satisfactory.