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Correlation energy contributions from low‐lying states to density functionals based on an electron gas with a gap
Author(s) -
Gutle Claudine,
Savin Andreas,
Krieger Joseph B.,
Chen Jiqiang
Publication year - 1999
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/(sici)1097-461x(1999)75:4/5<885::aid-qua53>3.0.co;2-f
Subject(s) - atomic orbital , rydberg formula , excited state , atomic physics , electronic correlation , complete active space , chemistry , valence (chemistry) , ground state , density functional theory , valence bond theory , physics , fermi gas , degeneracy (biology) , molecular orbital , electron , quantum mechanics , molecular physics , molecule , ion , ionization , bioinformatics , biology
Orbitals having negative orbital energies in density functional theory define a space for generating correlated wave functions and contributions to the correlation energies. The most important contribution from such states comes from the valence orbitals, while the Rydberg orbitals make a much smaller contribution. This provides a significant correction to the correlation energy obtained from a functional based on the uniform electron gas with a gap when there is a near degeneracy between the ground state and a two‐particle excited state. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 885–888, 1999