QED calculations of the $2p$-$2s$ transition energies in Li-like ions

Systematic QED calculations of ionization energies of the $2s$, $2p_{1\mathrm{/}2}$, and $2p_{3\mathrm{/}2}$ states, as well as the $2p_{1\mathrm{/}2}$–$2s$ and $2p_{3\mathrm{/}2}$–$2p_{1\mathrm{/}2}$ transition energies are performed for Li-like ions with the nuclear charge numbers $Z=10$–$100$. The convergence of QED perturbative expansion is improved by using the extended Furry picture, which starts from the Dirac equation with a local screening potential. An ab initio treatment is accomplished for one- and two-photon electron-structure QED effects and the one-photon screening of the self-energy and vacuum-polarization corrections. This is complemented with an approximate treatment of the two-photon QED screening and higher-order (three or more photon) electron-structure effects. As a result, the obtained theoretical predictions improve upon the accuracy achieved in previous calculations. Comparison with available experimental data shows a good agreement between theory and experiment. In most cases, the theoretical values surpass the experimental results in precision, with only a few exceptions. In the case of uranium and bismuth, the comparison provides one of the most stringent tests of bound-state QED in the strong-field regime. Alternatively, the obtained results can be employed for high-precision determinations of nuclear charge radii.