Relativistic calculations of the fine-structure intervals of the ns(2)np(2)P terms and the ionization energies of the Ca-, Sr- and Ba- ions

We report new calculations of the energy differences between the ns(1/2)(2)np(1/2) and ns(1/2)(2)np(3/2) levels of the Ca-, Sr- and Ba- ions; here n = 4, 5 and 6 for Ca-, Sr- and Ba-, respectively. The electron affinities of Ca, Pa and Sr have also been calculated. All estimates were obtained by performing a series of multiconfiguration Dirac-Fock calculations for the neutral atoms and their anions. Correlations among valence electrons in both the ground and excited states were included in these calculations. Our estimate of the fine structure of the ground stare of Sr- is in good agreement with recent measurements. Our estimates of the electron affinities of Ca, Sr and Ba are in reasonable agreement with experiment.