Density functional theory and chromium: Insights from the dimers
Rolf Würdemann1, Henrik H Kristoffersen2, Michael Moseler3
1Freiburger Materialforschungszentrum, Universität Freiburg, Stefan-Meier-Straße 21, D-79104 Freiburg, Germany.
The Journal of Chemical Physics
|April 3, 2015
Summary
Density functional theory approximations are evaluated for chromium clusters. Gradient-corrected functionals best describe chromium dimer binding energies and bond lengths, with Bayesian error estimation providing unambiguous results.
Area of Science:
- Computational Chemistry
- Materials Science
- Quantum Mechanics
Background:
- Investigating chromium clusters is crucial for understanding metallic bonding.
- Accurate theoretical descriptions of chromium dimers are challenging due to electron correlation effects.
- Previous studies show variations in binding energies and bond lengths for chromium clusters.
Purpose of the Study:
- To re-investigate binding in small chromium clusters.
- To identify the most suitable density functional theory (DFT) approximation for chromium systems.
- To clarify the electronic structure and bonding characteristics of chromium dimers in different charge states.
Main Methods:
- Utilized density functional theory (DFT) approximations.
- Focused on the three charge states of the chromium dimer (Cr2, Cr2+, Cr2-).
- Employed Bayesian error estimation to assess functional performance.
Main Results:
- Gradient-corrected (GGA) and meta-GGA functionals showed the best performance.
- Significant differences were observed between functionals within the same family.
- Bayesian error estimation unambiguously predicted correct energetics for all charge states.
- Small bond lengths are predicted exclusively for Cr2 and Cr2-, while Cr2+ and larger clusters exhibit long bond lengths.
Conclusions:
- The choice of DFT functional significantly impacts the description of chromium cluster binding.
- Accurate numerical representation of electron density and wave-functions is critical.
- Small bond lengths are characteristic of neutral and anionic chromium dimers, distinct from the cationic dimer and bulk chromium.
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