Oscillator strengths for spin-allowed electric dipole transitions in the cadmium isoelectronic sequence

We perform relativistic many-body perturbation theory calculations through second order to study the oscillator strengths for spin-allowed electric-dipole transitions among the lowlying levels of the cadmium isoelectronic sequence. In the rst-order calculations, we perform a frozen-core Dirac-Fock calculation. A linear combination of reference conguration wave functions is used to treat the intravalence correlations. The second-order calculations improve upon the wave functions by including the single-valence excitations, double-valence excitations, single-core excitations, double-core excitations, and single-valence single-core excitations of the reference congurations. Hence the second-order corrections take into account the intracore correlations, the core-valence correlations, and the intravalence correlations not included in the rst-order calculations. With the continuum contribution explicitely included in the B spline basis, both the bound-bound and the bound-continuum correlations are included. The total transition amplitudes in dierent gauges are in good agreement. The oscillator strengths are in excellent agreement with the experimental results based on ANDC analyses.