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Z‐expansion calculations of energy levels and transition probabilities in many‐electron atoms
Author(s) -
Layzer David
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560010605
Subject(s) - coulomb , perturbation theory (quantum mechanics) , electron , physics , inverse , dipole , wave function , atomic physics , ionization , effective nuclear charge , ionization energy , quantum electrodynamics , quantum mechanics , mathematics , ion , geometry
This paper reviews recent calculations of energy levels and transition probabilities in many‐electron atoms, based on expansions in inverse powers of the nuclear charge. Emphasis is given to simple approximation methods that apply to a wide class of atomic states. It is shown that the variational screening approximation often yields an accurate estimate of energy contributions of order Z −1 and that the relativistic contributions to the energy levels of light and moderately light atoms are comparable to or greater than the nonrelativistic contributions of order Z −1 when the degree of ionization exceeds 3 or 4. A new method is described for normalizing Coulomb wave functions that figure in the approximate evaluation of electric‐dipole transition integrals. It employs variational screening parameters and makes use of double perturbation theory.