Optimized Relativistic Many-Body Perturbation Theory Calculation of Wavelengths and Oscillator Strengths for Li-like Multicharged Ions

The radiative transition wavelengths and oscillator strengths for some Li-like multicharged ions are calculated within the relativistic many-body perturbation theory with the optimized Dirac-Kohn-Sham zeroth approximation and an effective taking the relativistic, exchange-correlation, nuclear, radiative effects into account. All correlation corrections of the second order and dominated classes of the higher orders diagrams have been considered (electrons screening, mass operator iterations etc). The method includes the generalized Glushkov-Ivanov-Ivanova procedure (relativistic energy approach) for generation of the optimal basis set of relativistic electron wave functions with fulfillment of the gauge invariance principle. To reach the latter, we focus on accurate consideration of the QED perturbation theory fourth-order (a second order of the atomic perturbation theory) Feynman diagrams, whose contribution into imaginary part of radiation width ImbE for the multielectron ions accounts for multibody correlation effects. A minimization of the functional ImbE leads to integral-differential Dirac-Kohn-Sham-like density functional equations. The magnetic interelectron interaction is accounted for in the lowest order on a 2 (a is the fine structure constant) parameter. The Lamb shift polarization part is taken into account in the modified Uehling-Serber approximation. Comparisons of our results on the radiative transition wavelengths and oscillator strengths for some transition in spectra of the Li-like multicharged ions (the nuclear charge Z = 21-30) with other comparable theoretical and experimental results are also given and discussed.