Energies, fine structures and transition wavelengths of the core-excited states in Be⁺ ions

The fine structures of doubly excited resonances of lithium-like beryllium are calculated using the saddle-point and saddle-point complex-rotation methods. A restricted variational method is used to obtain a more accurate value for the nonrelativistic energy. Relativistic and mass polarization corrections to the resonance energy are included. Transition wavelengths are also calculated and compared with other theories and experimental results.