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Calculations have been made for the 1s22s, 1s23s, 1s24s, 1s25s, 2S½ states of Li and Li-like ions. The functional form used allows for radial correlation in the inner shell and gives sufficient flexibility for describing the outer electron. The energy values obtained for the ground state are the best among calculations which do not introduce interelectronic coordinates or angular correlation. The energy values for the excited states differ by not more than 1% from the experimental values.
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Ritter et al. (1961) studied this question.
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