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Title: Density functional theory and chromium: Insights from the dimers

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{sub 2} and Cr{sub 2}{sup −}. Already for the dimer cation, solely long bond-lengths appear, similar to what is found in the trimer and in chromium bulk.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [1] ;  [4]
  1. Freiburger Materialforschungszentrum, Universität Freiburg, Stefan-Meier-Straße 21, D-79104 Freiburg (Germany)
  2. Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus (Denmark)
  3. Fraunhofer IWM, Wöhlerstrasse 11, D-79108 Freiburg (Germany)
  4. (Germany)
Publication Date:
OSTI Identifier:
22415571
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; BINDING ENERGY; BOND LENGTHS; CATIONS; CHARGE STATES; CHROMIUM; DENSITY FUNCTIONAL METHOD; DIMERS; ELECTRON DENSITY; FUNCTIONALS; GAIN; VARIATIONS; WAVE FUNCTIONS