Configuration-interaction study of differential correlation energies in Ca+, Ca, and Ca- - art. no. 052518

Configuration interaction (CI) calculations were carried out for Ca+ (4s S- 2, 3d D-2, and (4)p P-2(0)), Ca (4s(2) S-1 and 3d4s D-1), and Ca- (4s(2)4p P-2(0)), studying the convergence of Cl wave functions and energies with re spect to both the one-electron and configuration bases. The effects of the Ar-Like closed-shell core were included by considering excitations from the 3s and 3p subshells explicitly. The relativistic effects were estimated wi th Dirac-Fock calculations. The calculated ionization potentials were 6.080 , 7.820, and 9.180 eV for 4s S-2, 3d D-2, and 4p P-2(0), respectively, comp ared with respective experimental values of 6.113, 7.810, and 9.255 eV. The calculated excitation energy for 3d4s D-1 and electron affinity were 2.727 eV and 22 meV, respectively, which are in excellent agreement with the obs erved values of 2.709 eV and 21.3 meV.