ChemRxiv
These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
1/1

Stable Surfaces that Bind too Tightly: Can Range Separated Hybrids or DFT+U Improve Paradoxical Descriptions of Surface Chemistry?

preprint
submitted on 05.06.2019 and posted on 06.06.2019 by Qing Zhao, Heather Kulik
Approximate, semi-local density functional theory (DFT) suffers from delocalization error that can lead to a paradoxical overbinding of surface adsorbates and overestimation of surface stabilities in catalysis modeling. We investigate the effect of two widely applied approaches for delocalization error correction, i) affordable DFT+U (i.e., semi-local DFT augmented with a Hubbard U) and ii) hybrid functionals with an admixture of Hartree-Fock (HF) exchange, on surface and adsorbate energies across a range of rutile transition metal oxides widely studied for their promise as water splitting catalysts. We observe strongly row- and period-dependent trends with DFT+U, which increases surface formation energies only in early transition metals (e.g., Ti, V) and decreases adsorbate energies only in later transition metals (e.g., Ir, Pt). Both global and local hybrids destabilize surfaces and reduce adsorbate binding across the periodic table, in agreement with higher-level reference calculations. Density analysis reveals why hybrid functionals correct both quantities, whereas DFT+U does not. We recommend local, range-separated hybrids for the accurate modeling of catalysis in transition metal oxides at only a modest increase in computational cost over semi-local DFT.

Funding

Simultaneous mitigation of density and energy errors in approximate DFT for transition metal chemistry

Basic Energy Sciences

Find out more...

History

Email Address of Submitting Author

hjkulik@mit.edu

Institution

Massachusetts Institute of Technology

Country

United States

ORCID For Submitting Author

0000-0001-9342-0191

Declaration of Conflict of Interest

The authors declare no conflict of interest.

Exports