Correlation holes and wavefunctions for the 1S, 1P°, and 3P° states of Be, B+, and C2+

Abstract

``Average'' pair distribution functions, P(r12), are calculated both from the Hartree-Fork (HF) and configuration interaction (CI) wavefunctions for the 1P°, 3P°, and 1S states of Be, B+, and C2+. The average electronic separation, <r12>, and interelectronic interaction energy, <r12−1>, are also obtained from the CI and HF wavefunctions. Reflecting the difference of the degree of correlation (between the CI and HF wavefunctions), the CI wavefunctions give a larger interelectronic distance than the HF wavefunctions except for the 1P° state of Be. For Be 1P°, the CI wavefunction reduces the average electronic separation in comparison with the HF wavefunction; this contradicts the general idea that the calculated electron pair distribution function for a CI wavefunction is more spread out than for the HF counterpart. This reduction of <r12> is discussed in connection with the fact that the 2p orbital obtained by the HF calculation in Be 1P° is much more diffuse that that in the other states and that the 2p electron distribution is contracted by the CI calculation. Apart from Be 1P°, the difference between the two functions, P(r12), calculated from the CI and HF wavefunctions, gives a shallower correlation hole for 3P° than for 1P° and 1S. This is because in the HF calculation the Pauli principle keeps the L-shell electrons apart in the triplet state.