Abstract
Z-expansions are based on Rayleigh–Schrödinger perturbation theory (RSPT) solutions of Schrödinger's equation. Higher order corrections must be calculated using approximate wave functions, with inevitable loss of accuracy. So, it is entirely possible that estimates derived from a Z-expansion truncated at a relatively high order are no more reliable than those obtained from a lower order truncation, in spite of apparent numerical convergence of the coefficients. The first-order screening approximation result suggests that a very simple description of many atomic properties results from assuming a hydrogenic model of the atom but with an appropriately screened nucleus. The primitive screening approximation is qualitatively highly successful and quantitatively useful with increasing Z, while a representation based on only a few additional computed RSPT coefficients is capable of very high accuracy.
Original language | English |
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Pages (from-to) | 195-220 |
Number of pages | 26 |
Journal | Advances in Atomic and Molecular Physics |
Volume | 25 |
Issue number | C |
DOIs | |
State | Published - 1 Jan 1989 |