Dielectronic capture processes in highly charged uranium ions

Dielectronic capture processes in highly charged uranium ions are studied in the isolated-resonance, distorted-wave approximation. A fully relativistic Dirac-Fock method is employed to calculate resonant transfer and excitation cross sections for collisions of U⁹⁰⁺ and U⁸⁹⁺ with H₂ and dielectronic recombination cross sections associated with the 2p{→}2s stabilizing transition of U⁸⁹⁺. A semirelativistic method based on the previously developed autostructure code is found to give cross sections in good agreement with the Dirac-Fock method in all cases. When the Dirac-Fock method is further extended to include the effect of the two-body Breit interaction, substantial changes are found in certain low-energy cross sections associated with K-shell resonant transfer and excitation, but little change is found in the {Δ}n=0 dielectronic recombination cross sections.