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An analysis of nonlocal density functionals in chemical bonding
Author(s) -
Leeuwen Robert Van,
Baerends Evert Jan
Publication year - 1994
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.560520405
Subject(s) - work (physics) , space (punctuation) , density gradient , statistical physics , bond energy , physics , energy (signal processing) , chemical bond , local density approximation , bond length , density functional theory , energy density , molecule , chemistry , quantum mechanics , theoretical physics , philosophy , linguistics
Abstract In this work, we carry out an analysis of the gradient‐corrected density functionals in molecules that are used in the Kohn–Sham density functional approach. We concentrate on the special features of the exchange and correlation energy densities and exchange and correlation potentials in the bond region. By comparing to the exact Kohn–Sham potential, it is shown that the gradient‐corrected potentials build in the required peak in the bond midplane, but not completely correctly. The gradient‐corrected potentials also exhibit wrong asymptotic behavior. Contributions from different regions of space (notably bond and outer regions) to nonlocal bonding energy contributions are investigated by integrating the exchange and correlation energy densities in various spatial regions. This provides an explanation of why the gradient corrections reduce the local density approximation ( LDA ) overbinding of molecules. It explains the success of the presently used nonlocal corrections, although it is possible that there is a cancellation of errors, too much repulsion being derived from the bond region and too little from the outer region. © John Wiley & Sons, Inc.