Multiconfiguration Dirac-Fock calculations for the ${2s}^{21}{S}_0–2s2p{}^3{P}_1$ intercombination transition in C III are revisited. To improve the accuracy, the orbital sets for the initial- and final-state wave functions were not restricted to be the same, but were optimized independently. The calculated $2s2p{}^{3}P$ fine-structure splitting and the ${2s}^{21}{S}_0–{2s2p}^3{P}_1$ transition energy are in good agreement with experiment. The predicted transition rate $A=102.9\mathrm{}\pm 1.5{\mathrm{s}}^{\mathrm{-}1}$ is in agreement with a recent storage-ring measurement by Doerfert et al. [Phys. Rev. Lett. 78, 4355 (1997)]. Results are also presented for the allowed ${2s}^{21}{S}_0–2s2p{}^1{P}_1$ transition and the ${2s}^{21}{S}_0–2s2p{}^3{P}_2$ magnetic quadrupole transition.

• Received 2 April 1997

DOI:https://doi.org/10.1103/PhysRevA.57.4967