Accurate CI and Hylleraas-CI wave functions for the atomic effects in the whole-atom-nuclear beta-decay of the Li atom

Abstract

In this review we study the level of accuracy of the electronic wave functions which is necessary to describe properly the atomic effects during nuclear beta-decay. In the case of the beta- decay in the Li atom into Be+ ion we compare the numerical values of the transition probabilities from the S-, P-, D-low-lying states of the initial atom and final ion calculated using both Hylleraas-Configuration Interaction (Hy-CI) and Configuration Interaction (CI) with Slater orbitals wave functions. In addition using the CI method the transition probabilities from F, G, H and I low-lying states have been calculated. The average of the absolute deviation of the transition probabilities distribution for low-lying S-states is <0.15%, for P-states <0.5%, and larger for D- and higher energy states. The numerical results demonstrate that for low-lying states the atomic effect parameters in beta-decay can be calculated with sufficient accuracy using CI wave functions constructed with Slater orbitals. This result opens a new avenue for the accurate calculation of atomic effects during the beta-decay in heavier atoms and molecules.