Calculations on the low-lying excited2Sstates of some members of the Li isoelectronic series

Abstract

The results of variational calculations using large Hylleraas basis sets are reported for some low-lying excited ${}_{}{}^2{}_{}{}^{}$S states of the Li i isoelectronic series for 3≤Z≤10. The 3 ${}_{}{}^2{}_{}{}^{}$S, 4 ${}_{}{}^2{}_{}{}^{}$S, and 5 ${}_{}{}^2{}_{}{}^{}$S states are studied for Li i and Be i i, and the 3 ${}_{}{}^2{}_{}{}^{}$S and 4 ${}_{}{}^2{}_{}{}^{}$S states are investigated for the other ions. The nonrelativistic energies obtained are the lowest-upper-bound estimates so far reported. In some cases the literature estimates of these energies are found to be in error, as they lie above the results of the present calculations. Hyperfine coupling constants, specific-mass shifts, transition isotope shifts, electron density at the nucleus, and the individual energy components are reported. The rates of convergence of the various expectation values are discussed.