Highly accurate three-body wavefunctions for the 23S(L = 0) states in two-electron ions

Abstract

The exponential representation is used to construct highly accurate wavefunctions for the triplet states in various two-electron helium-like ions. It is shown that the exponential variational expansion in relative coordinates (r32, r31 and r21) provides a very high accuracy for the triplet 23S(L = 0) states in light two-electron ions. The developed methods are used to determine the highly accurate non-relativistic energies and other bound state properties for the 23S(L = 0) state in a number of He-like two-electron ions Li+, Be2+, B3+, C4+, N5+, O6+, F7+ and Ne8+. To represent the computed energies of these ions the Q−1 expansion is applied. The asymptotic form of the 23S(L = 0) state wavefunctions at large electron–nuclear distances for the He-like ions is briefly discussed. We also consider the hyperfine structure splitting in the 23S(L = 0) state of the helium-like ions with non-zero nuclear spin. For each of the considered two-electron ions one can determine the isotopic shifts by using our approach based on the derived interpolation formula. The lowest order QED corrections are also determined for the triplet states in all mentioned two-electron ions.