Fine structure of Ca^-, Sr^-, Ba^-, and Ra^- from the many-body theory calculation

Atomic many-body theory methods are used to calculate the fine structure of negative ions formed by binding a p electron into an open shell, Ca^-, Sr^-, Ba^-, and Ra^-. This binding is due to a strong correlation potential acting between the electron and the neutral atom. Comparison with experimental data shows that the second order many-body perturbation theory calculation overestimates the correlation potential by 10% to 15%. Scaling factors are introduced in the correlation potential to reproduce experimental binding energies of the lower p_1/2 components. This procedure yields fine-structure intervals in excellent agreement with experiment for Ca^-, Sr^-, and Ba^-, and allows us to predict that in Ra^- the p_1/2 state is bound by 100 meV, and p_3/2 is a resonance at 16 meV in the continuum.