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Construction of accurate Kohn–Sham potentials for the lowest states of the helium atom: Accurate test of the ionization‐potential theorem
Author(s) -
Lindgren I.,
Salomonson S.,
Möller F.
Publication year - 2005
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.20530
Subject(s) - helium atom , atomic physics , eigenvalues and eigenvectors , kohn–sham equations , ionization energy , atomic orbital , ionization , ground state , physics , quantum mechanics , atom (system on chip) , fock space , electron , helium , chemistry , density functional theory , ion , computer science , embedded system
Accurate local Kohn–Sham potentials have been constructed for the ground 1 s 2 1 S state and, in particular, for the lowest triplet 1 s 2 s 3 S state of the helium atom, using electron densities from many‐body calculations and the procedure of van Leeuwen and Baerends. The resulting Kohn–Sham orbitals reproduce the many‐body densities very accurately; furthermore, we have demonstrated that the negative of the energy eigenvalue of the outermost electron orbital agrees with the corresponding ionization energy with extreme accuracy. The procedure is also applied to the Hartree–Fock density of the 1 s 2 s 3 S state, and the Kohn–Sham eigenvalue of the 2 s orbital is found to agree very well with the corresponding Hartree–Fock eigenvalue, which is the negative of the ionization energy in this model due to Koopmans' theorem. The results clearly demonstrate that there is no conflict between the locality of the Kohn–Sham potential and the exclusion principle, as claimed by Nesbet. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005