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Abstract Perturbation methods are employed to calculate a wide range of atomic parameters relating to the ground states of the helium iso-electronic sequence, the unperturbed eigenfunctions being products of screened hydrogenic orbitals. The screening constant enters as a disposable parameter. A means of choosing it is described which yields different values for different atomic properties. It is shown quantitatively that the simple calculations involved thereby lead to results of high accuracy.
Dalgarno et al. (Tue,) studied this question.