Theoretical oscillator strengths for spin-allowed electric-dipole transitions in Zn-like ions

We have performed a relativistic many-body perturbation theory calculation up to second order to study the transition amplitudes, Einstein A coefficients, and oscillator strengths for the spin-allowed electric-dipole transitions in the Zn-like ions Zn, Ge2+, As3+, Kr6+, Nb11+, and Mo12+. All possible transitions among the first 13 levels of these ions have been studied. The total transition amplitudes obtained in different gauges are in excellent agreement. The gauge dependences of the first and second order, and the total transition amplitudes are derived. A theoretical justification for the small gauge dependence of the total transition amplitude is given. The present calculations agree well with experiment for all ions except for the neutral Zn atom.