NATURAL EXPANSIONS OF CI WAVE-FUNCTIONS AND ANALYSIS OF COULOMB CORRELATIONS FOR HE(2P(2) P-3)-LIKE IONS

Natural expansions are presented for energetically acceptable configuration-interaction (CI) wavefunctions for the He(2p2 3P)-like ions when 1 less-than-or-equal-to Z less-than-or-equal-to 4. The symmetry of the natural orbitals and their occupation numbers are contrasted with existing results for the ls2 1S ground state. Moreover, results are given for Coulomb holes, partial holes and interparticle expectation values [r12n], where -2 less-than-or-equal-to n less-than-or-equal-to + 2. Comparisons are made with recently reported findings when the 2p2 3P states were described by 'benchmark' explicity-correlated (EC) wavefunctions. The natural expansions of the CI functions allowed us to explore the origin and convergence of the effects of Coulomb correlation. In particular, the analysis also highlighted significant changes in the relative importance of angular and radial correlation for these doubly-excited states as Z was increased.