Abstract
Density functional approximations for the exchange-correlation energy EDFAxc of an electronic system are often improved by admixing some exact exchange Ex: Exc≊EDFAxc+(1/n)(Ex−EDFAx). This procedure is justified when the error in EDFAxc arises from the λ=0 or exchange end of the coupling-constant integral ∫10 dλ EDFAxc,λ. We argue that the optimum integer n is approximately the lowest order of Görling–Levy perturbation theory which provides a realistic description of the coupling-constant dependence Exc,λ in the range 0≤λ≤1, whence n≊4 for atomization energies of typical molecules. We also propose a continuous generalization of n as an index of correlation strength, and a possible mixing of second-order perturbation theory with the generalized gradient approximation.
Keywords
GeneralizationMixing (physics)Perturbation theory (quantum mechanics)Coupling constantPerturbation (astronomy)MathematicsConstant (computer programming)Integer (computer science)Approximation errorPhysicsMathematical analysisStatistical physicsQuantum mechanicsComputer science
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Publication Info
- Year
- 1996
- Type
- article
- Volume
- 105
- Issue
- 22
- Pages
- 9982-9985
- Citations
- 6285
- Access
- Closed
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Cite This
John P. Perdew,
Matthias Ernzerhof,
Kieron Burke
(1996).
Rationale for mixing exact exchange with density functional approximations.
The Journal of Chemical Physics
, 105
(22)
, 9982-9985.
https://doi.org/10.1063/1.472933
Identifiers
- DOI
- 10.1063/1.472933