Relativistic many-body calculations of excitation energies and oscillator strengths in Ni-like ions

Excitation energies for 3l-4l^' particle-hole states of Ni-like ions are determined to second order in relativistic many body perturbation theory. The calculations start from a closed-shell Dirac-Fock potential, and include second-order Coulomb and Breit-Coulomb interactions. Retarded electric-dipole matrix elements (in length and velocity forms) are calculated in second order for transitions from excited 3l-4l^' states to the closed-shell ground state. Wavelengths for 3-4 and 4-4 transitions are compared with experimental data, and with other high-precision calculations. Trends of oscillator strengths as functions of nuclear charge Z are shown graphically for selected transitions.