Adiabatic hyperspherical treatment of lithiumPo2states

The lithium atom is studied by treating all three electrons on an equal footing using hyperspherical coordinates. The use of asymptotic base states improves the convergence of the potential curve calculation dramatically at large $R$. A potential curve plot suggests that a few localized pathways dominate the formation and decay of the lowest triply-excited state, $2s^{2}2p$. A quantitative study of the lowest state of this symmetry, $1s^{2}2p$, shows that the adiabatic approximation in hyperspherical coordinates gives an improvement over independent-electron methods, owing primarily to its inclusion of radial correlation effects at small distances $R$.