Density functional theory and chromium: Insights from the dimers

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DOI

  • Rolf Wuerdemann, Univ Freiburg, University of Freiburg, Freiburger Mat Forschungszentrum
  • ,
  • Henrik H. Kristoffersen
  • ,
  • Michael Moseler, Univ Freiburg, University of Freiburg, Phy Inst
  • ,
  • Michael Walter, Fraunhofer IWM

The binding in small Cr clusters is re-investigated, where the correct description of the dimer in three charge states is used as criterion to assign the most suitable density functional theory approximation. The difficulty in chromium arises from the subtle interplay between energy gain from hybridization and energetic cost due to exchange between s and d based molecular orbitals. Variations in published bond lengths and binding energies are shown to arise from insufficient numerical representation of electron density and Kohn-Sham wave-functions. The best functional performance is found for gradient corrected (GGA) functionals and meta-GGAs, where we find severe differences between functionals from the same family due to the importance of exchange. Only the "best fit" from Bayesian error estimation is able to predict the correct energetics for all three charge states unambiguously. With this knowledge, we predict small bond-lengths to be exclusively present in Cr-2 and Cr-2(-). Already for the dimer cation, solely long bond-lengths appear, similar to what is found in the trimer and in chromium bulk. (c) 2015 AIP Publishing LLC.

Original languageEnglish
Article number124316
JournalJournal of Chemical Physics
Volume142
Issue12
Number of pages9
ISSN0021-9606
DOIs
Publication statusPublished - Mar 2015

    Research areas

  • AUGMENTED-WAVE METHOD, GENERALIZED GRADIENT APPROXIMATION, TRANSITION-METAL DIMERS, LOCAL-SPIN-DENSITY, GROUND-STATE, BASIS-SETS, PHOTOELECTRON-SPECTROSCOPY, ELECTRONIC-STRUCTURE, PERTURBATION-THEORY, BOND-ENERGIES

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