Relativistic many-body calculations of excitation energies and transition rates in ytterbiumlike ions

Excitation energies, oscillator strengths, and transition rates are calculated for (5d²+5d6s+6s²)-(5d6p+5d5f+6s6p) electric dipole transitions in Yb-like ions with nuclear charges Z ranging from 72 to 100. Relativistic many-body perturbation theory (RMBPT), including the retarded Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a [Xe]4f¹⁴ core Dirac-Fock potential. First-order RMBPT is used to obtain intermediate coupling coefficients, and second-order RMBPT is used to determine matrix elements. A detailed discussion of the various contributions to energy levels and dipole matrix elements is given for ytterbiumlike rhenium, Z=75. The resulting transition energies are compared with experimental values and with results from other recent calculations. Trends of excitation energies, line strengths, oscillator strengths, and transition rates as functions of nuclear charge Z are shown graphically for selected states and transitions. These calculations are presented as a theoretical benchmark for comparison with experiment and theory.