Energy and lifetime of core-excited Be⁺ resonances

The energies, shifts, widths, and radiative rates of double excited Be⁺ resonances are calculated using the saddle point and saddle-point complex-rotation methods. A restricted variational method is used to extrapolate a better nonrelativistic energy. Relativistic effects are included using first-order perturbation theory. These results are used to make a better understanding of observed Be⁺ spectra.