Transition frequencies between 2S and 2P states of lithium-like ions

The Schrödinger equation for the 2S and 2P states of the lithium-like ions Z = 5–7, 9–10 is solved by using the Rayleigh-Ritz variational method in Hylleraas coordinates. The leading-order relativistic and QED corrections are calculated perturbatively and higher-order corrections are estimated. The transition frequencies between the 2S_1/2 and 2P_J (J = 1/2, 3/2) states are determined and compared with experimental and other theoretical results. Specifically, isotope shifts are also calculated for B²⁺.