Lifetimes of 4 p 5 4 d levels in highly ionized atoms

Energy levels, lifetimes, and wave function compositions have been computed for all atomic states of the $4p^6$ and $4p^{5}4d$ configurations using the multiconfiguration Dirac-Hartree-Fock method. Calculations were done by parity and the configuration state function expansions were obtained by allowing single and double substitutions from the the $4p^6$ and $4p^{5}4d$ single references with orbitals in an orbital set that was extended to $n$ = 7 and all possible angular symmetries. Lifetimes are computed from $E1$ , $E2$ , and $M1$ transitions between these levels. Energy levels and transition energies (or wavelengths) are compared with other theory and experiment, when available. Transition data for the $4p^6{}^{1}S_0-4p^{5}4dJ$ = 1 transitions are investigated in detail with respect to convergence of transition energies and the length and velocity forms of the line strengths. By classifying the upper states by $J$ , parity ( $\pi$ ), and position, the compositions of the states with the same three quantum number change smoothly as a function of the nuclear charge $Z$ and transition energies and transition matrix elements can be approximated by polynomial expressions in $Z$ . A zero in the transition matrix element for the ${}^{1}S_0\text{-}{}^3{P}_1^o$ transition leads to a long lifetime at $Z$ ≈ 58.