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Core polarization and relativistic effects competition in the first ionization potentials for some systems in the Cu, Ag, and Au isoelectronic sequences
Author(s) -
Migdalek J.,
Baylis W. E.
Publication year - 1984
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.560250109
Subject(s) - atomic physics , ionization , polarizability , relativistic quantum chemistry , polarization (electrochemistry) , dipole , ion , chemistry , hamiltonian (control theory) , valence (chemistry) , ionization energy , electron , physics , core electron , quantum mechanics , molecule , mathematical optimization , mathematics
Abstract Single‐configuration relativistic Hartree–Fock values of the first ionization potentials for Cu through Kr 7+ , Ag through I 6+ , and Au through Pb 3+ are computed in “frozen” and “relaxed core” approximations with and without allowance for core polarization. Effects of polarization of the atomic core by the valence electron are included by introducing a polarization potential in the one‐electron Hamiltonian of the valence electron. The core polarization potential depends on two parameters, the static dipole polarizability of the core α and the cut‐off radius r 0 , which are chosen independently of the ionization potential data. It is demonstrated that by including the core polarization potential with α and r 0 parameters, which are simply chosen instead of being empirically fitted, it is still possible to account, on the average, for at least 70% of the discrepancy between the single‐configuration relativistic Hartree–Fock ionization potentials and the experiment, a discrepancy usually ascribed to the contribution of valence‐core electron correlations, and to bring the theoretical ionization potentials to an average agreement with experiment of around 1%. It can be concluded from this study that for low and medium Z elements the core polarization dominates for neutral systems or systems in low ionization stages, whereas for highly ionized systems the relativistic effects prevail. For heavy elements, however, the core polarization influence is comparable to the relativistic one only for neutral systems, whereas for ions the relativistic effects are overwhelmingly predominant.