CONFIGURATION-INTERACTION STUDY OF THE DIFFERENTIAL CORRELATION ENERGIES AMONG THE LOWEST S-2, D-2, AND P-2(0) STATES OF CA+

In order to analyze the differential correlation energies among the lowest 2S(4s1), 2D(3d1), and 2Po(4p1) states of Ca+, configuration-interaction calculations have been carried out for the three states. The results reveal that the 2D state has a larger core-valence correlation energy by 0.66 and 0.91 eV and a smaller core-core correlation energy by 0.38 and 0.39 eV than the 2S and 2Po states, respectively. Based on an analysis of the computed correlation energies in terms of contributions by various excitation types, the differential core-core correlation energy is interpreted as the difference in the contribution from the 3p2dd excitation between the 2D state and the others. The 3s intrashell correlation energies as well as the 3s-3p intershell correlation energies are uniformly equal among the three states. © 1994 The American Physical Society.