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Fractional spins and static correlation error in density functional theory.

Publication ,  Journal Article
Cohen, AJ; Mori-Sánchez, P; Yang, W
Published in: The Journal of chemical physics
September 2008

Electronic states with fractional spins arise in systems with large static correlation (strongly correlated systems). Such fractional-spin states are shown to be ensembles of degenerate ground states with normal spins. It is proven here that the energy of the exact functional for fractional-spin states is a constant, equal to the energy of the comprising degenerate pure-spin states. Dramatic deviations from this exact constancy condition exist with all approximate functionals, leading to large static correlation errors for strongly correlated systems, such as chemical bond dissociation and band structure of Mott insulators. This is demonstrated with numerical calculations for several molecular systems. Approximating the constancy behavior for fractional spins should be a major aim in functional constructions and should open the frontier for density functional theory to describe strongly correlated systems. The key results are also shown to apply in reduced density-matrix functional theory.

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Published In

The Journal of chemical physics

DOI

EISSN

1089-7690

ISSN

0021-9606

Publication Date

September 2008

Volume

129

Issue

12

Start / End Page

121104

Related Subject Headings

  • Chemical Physics
  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences
 

Citation

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Cohen, A. J., Mori-Sánchez, P., & Yang, W. (2008). Fractional spins and static correlation error in density functional theory. The Journal of Chemical Physics, 129(12), 121104. https://doi.org/10.1063/1.2987202
Cohen, Aron J., Paula Mori-Sánchez, and Weitao Yang. “Fractional spins and static correlation error in density functional theory.The Journal of Chemical Physics 129, no. 12 (September 2008): 121104. https://doi.org/10.1063/1.2987202.
Cohen AJ, Mori-Sánchez P, Yang W. Fractional spins and static correlation error in density functional theory. The Journal of chemical physics. 2008 Sep;129(12):121104.
Cohen, Aron J., et al. “Fractional spins and static correlation error in density functional theory.The Journal of Chemical Physics, vol. 129, no. 12, Sept. 2008, p. 121104. Epmc, doi:10.1063/1.2987202.
Cohen AJ, Mori-Sánchez P, Yang W. Fractional spins and static correlation error in density functional theory. The Journal of chemical physics. 2008 Sep;129(12):121104.

Published In

The Journal of chemical physics

DOI

EISSN

1089-7690

ISSN

0021-9606

Publication Date

September 2008

Volume

129

Issue

12

Start / End Page

121104

Related Subject Headings

  • Chemical Physics
  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences