Simulation of heme using DFT + U : A step toward accurate spin-state energetics

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Damián A. Scherlis
  • Matteo Cococcioni
  • Patrick Sit
  • Nicola Marzari

Detail(s)

Original languageEnglish
Pages (from-to)7384-7391
Journal / PublicationJournal of Physical Chemistry B
Volume111
Issue number25
Publication statusPublished - 28 Jun 2007
Externally publishedYes

Abstract

We investigate the DFT + U approach as a viable solution to describe the low-lying states of ligated and unligated iron heme complexes. Besides their central role in organometallic chemistry, these compounds represent a paradigmatic case where LDA, GGA, and common hybrid functionals fail to reproduce the experimental magnetic splittings. In particular, the imidazole pentacoordinated heme is incorrectly described as a triplet by all usual DFT flavors. In this study, we show that a U parameter close to 4 eV leads to spin transitions and molecular geometries in quantitative agreement with experiments and that DFT + U represents an appealing tool in the description of iron porphyrin complexes, at a much reduced cost compared to correlated quantum-chemistry methods. The possibility of obtaining the U parameter from first principles is explored through a self-consistent linear-response formulation. We find that this approach, which proved to be successful in other iron systems, produces in this case some overestimation with respect to the optimal values of U. © 2007 American Chemical Society.

Citation Format(s)

Simulation of heme using DFT + U: A step toward accurate spin-state energetics. / Scherlis, Damián A.; Cococcioni, Matteo; Sit, Patrick et al.
In: Journal of Physical Chemistry B, Vol. 111, No. 25, 28.06.2007, p. 7384-7391.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review