The first nonrelativistic lower bound to the ground state of the lithium atom is given with EO > -7.47816 au using the method of variance minimization and an extension of Temple's formula. With large Hylleraas-CI basis sets, high-precision upper bounds and isotope shifts are calculated for the three lowest 2S states of the lithium atom, which are the best to date.
Accurate lower and upper bounds for the nonrelativistic ground state energies E, of the real systems ,He, H-, D-, and T-were calculated by the method of variance minimization using wave functions which include logarithmic terms. In addition, an analogous treatment with an infinite mass approximation for H-, He, and the isoelectronic series up to 2 = 10 was carried out. Especially for H-and He the results (a.u.) are given by -0.52775101712297, < E,(H-) < -0.52775101654373,These values have an absolute error smaller than 1.28 . lo-, cm-' for H-and 3.10 .cm-' for He. Moreover it is shown that a variation of nuclear mass m, for the H-species does not produce a second discrete eigenvalue.
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