Variational upper bounds for low-lying states of lithium
copyright American Physical Society http://dx.doi.org/10.1103/PhysRevA.83.034503
We present improved calculations of variational energy eigenvalues for the 1s22s2S, 1s23s2S, and 1s22p2P states of lithium using basis sets with up to 30 224 terms in Hylleraas coordinates. The nonrelativistic energies for infinite nuclear mass are -7.4780603239101437(45) a.u. for 1s22s2S, -7. 3540984214443164(32) a.u. for 1s23s2S, and -7.4101565326516(5) a.u. for 1s22p2P, which represent the most accurate variational upper bounds to date. An important advantage of the basis sets with multiple distance scales is their exceptional numerical stability. © 2011 American Physical Society.