Testing exchange–correlation functionals at fractional electron numbers

Malek, Ali; Peng, Degao; Yang, Weitao; Balawender, Robert; Holas, A.

doi:10.1007/s00214-014-1559-5

Cited by 2 publications

(1 citation statement)

References 53 publications

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“…Hybrid approximations combining a fraction of HF exchange with a semilocal DFA help to reduce fractional-charge errors, even though they still give significantly convex energy curves [5,8]. Long-range corrected (LC) [12] or Coulombattenuated-method (CAM) [13] approximations introducing 100% of HF exchange at long-range electronelectron distances tend to further reduce fractionalcharge errors [5,8,[14][15][16]. Moving now to approximations depending on virtual orbitals, second-order Møller-Plesset (MP2) perturbation theory was found to give very small fractional-charge errors [17,18].…”

Section: Introductionmentioning

confidence: 99%

Fractional-charge and fractional-spin errors in range-separated density-functional theory

Mussard

Toulouse

2016

Molecular Physics

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We investigate fractional-charge and fractional-spin errors in range-separated density-functional theory. Specifically, we consider the range-separated hybrid (RSH) method which combines long-range Hartree-Fock (HF) exchange with a short-range semilocal exchange-correlation density functional, and the RSH+MP2 method which adds long-range second-order Møller-Plesset (MP2) correlation. Results on atoms and molecules show that the fractional-charge errors obtained in RSH are much smaller than in the standard Kohn-Sham (KS) scheme applied with semilocal or hybrid approximations, and also generally smaller than in the standard HF method. The RSH+MP2 method tends to have smaller fractional-charge errors than standard MP2 for the most diffuse systems, but larger fractional-charge errors for the more compact systems. Even though the individual contributions to the fractional-spin errors in the H atom coming from the short-range exchange and correlation density-functional approximations are smaller than the corresponding contributions for the full-range exchange and correlation density-functional approximations, RSH gives fractional-spin errors that are larger than in the standard KS scheme and only slightly smaller than in standard HF. Adding long-range MP2 correlation only leads to infinite fractional-spin errors. This work clarifies the successes and limitations of range-separated density-functional theory approaches for eliminating self-interaction and static-correlation errors.arXiv:1607.03621v1 [physics.chem-ph]

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Section: Introductionmentioning

confidence: 99%

Fractional-charge and fractional-spin errors in range-separated density-functional theory

Mussard

Toulouse

2016

Molecular Physics

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Describing strong correlation with fractional-spin correction in density functional theory

Yang

2018

Proc. Natl. Acad. Sci. U.S.A.

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An effective fractional-spin correction is developed to describe static/strong correlation in density functional theory. Combined with the fractional-charge correction from recently developed localized orbital scaling correction (LOSC), a functional, the fractional-spin LOSC (FSLOSC), is proposed. FSLOSC, a correction to commonly used functional approximations, introduces the explicit derivative discontinuity and largely restores the flat-plane behavior of electronic energy at fractional charges and fractional spins. In addition to improving results from conventional functionals for the prediction of ionization potentials, electron affinities, quasiparticle spectra, and reaction barrier heights, FSLOSC properly describes the dissociation of ionic species, single bonds, and multiple bonds without breaking space or spin symmetry and corrects the spurious fractional-charge dissociation of heteroatom molecules of conventional functionals. Thus, FSLOSC demonstrates success in reducing delocalization error and including strong correlation, within low-cost density functional approximation.

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Testing exchange–correlation functionals at fractional electron numbers

Cited by 2 publications

References 53 publications

Fractional-charge and fractional-spin errors in range-separated density-functional theory

Fractional-charge and fractional-spin errors in range-separated density-functional theory

Describing strong correlation with fractional-spin correction in density functional theory

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