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Nonadiabatic core polarization and penetration correction in alkali‐like atoms: Model computations on excited states of helium
Author(s) -
Young Ralph H.,
Deal Walter J.
Publication year - 1975
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.560090508
Subject(s) - adiabatic process , excited state , helium atom , atomic physics , electron , adiabatic theorem , wave function , helium , physics , electronic correlation , polarization (electrochemistry) , core electron , quantum mechanics , chemistry
Abstract Correlation between the motion of a highly excited outer electron and that of the remaining ionic “core” of an atom is generally treated in an adiabatic approximation, in which it is assumed that the outer electron affects the core in the same way as a stationary point charge. An alternative approach to this correlation problem which avoids the adiabatic approximation is tested here on the 1 s 2 p , 1 s 3 d , and 1 s 4 f states of helium. The results provide the first accurate test of the adiabatic approximation and of a simple correction for the nonzero velocity of the outer electron. The approach used here is based on neglect, in the “correlation” part of the wave function, of the possibility that the outer electron comes closer to the nucleus than any core electron (“penetration”). A correction for this neglect is derived and tested on a version of the adiabatic approximation that likewise neglects penetration.