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Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure.

Publication ,  Journal Article
Mori-Sánchez, P; Wu, Q; Yang, W
Published in: The Journal of chemical physics
August 8, 2005

We have developed a second-order perturbation theory (PT) energy functional within density-functional theory (DFT). Based on PT with the Kohn-Sham (KS) determinant as a reference, this new ab initio exchange-correlation functional includes an exact exchange (EXX) energy in the first order and a correlation energy including all single and double excitations from the KS reference in the second order. The explicit dependence of the exchange and correlation energy on the KS orbitals in the functional fits well into our direct minimization approach for the optimized effective potential, which is a very efficient method to perform fully self-consistent calculations for any orbital-dependent functionals. To investigate the quality of the correlation functional, we have applied the method to selected atoms and molecules. For two-electron atoms and small molecules described with small basis sets, this new method provides excellent results, improving both second-order Moller-Plesset expression and any conventional DFT results significantly. For larger systems, however, it performs poorly, converging to very low unphysical total energies. The failure of PT based energy functionals is analyzed, and its origin is traced back to near degeneracy problems due to the orbital- and eigenvalue-dependent algebraic structure of the correlation functional. The failure emerges in the self-consistent approach but not in perturbative post-EXX calculations, emphasizing the crucial importance of self-consistency in testing new orbital-dependent energy functionals.

Duke Scholars

Published In

The Journal of chemical physics

ISSN

0021-9606

Publication Date

August 8, 2005

Volume

123

Issue

6

Start / End Page

62204

Related Subject Headings

  • Chemical Physics
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences
 

Citation

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Mori-Sánchez, P., Wu, Q., & Yang, W. (2005). Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure. The Journal of Chemical Physics, 123(6), 62204.
Mori-Sánchez, P., Q. Wu, and W. Yang. “Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure.The Journal of Chemical Physics 123, no. 6 (August 8, 2005): 62204.
Mori-Sánchez P, Wu Q, Yang W. Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure. The Journal of chemical physics. 2005 Aug 8;123(6):62204.
Mori-Sánchez, P., et al. “Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure.The Journal of Chemical Physics, vol. 123, no. 6, Aug. 2005, p. 62204.
Mori-Sánchez P, Wu Q, Yang W. Orbital-dependent correlation energy in density-functional theory based on a second-order perturbation approach: success and failure. The Journal of chemical physics. 2005 Aug 8;123(6):62204.

Published In

The Journal of chemical physics

ISSN

0021-9606

Publication Date

August 8, 2005

Volume

123

Issue

6

Start / End Page

62204

Related Subject Headings

  • Chemical Physics
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences