Theoretical and Computational Chemistry

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

Heather Kulik Massachusetts Institute of Technology


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.


Thumbnail image of MO2Surfaces_v1.pdf
download asset MO2Surfaces_v1.pdf 3 MB [opens in a new tab]

Supplementary material

Thumbnail image of surface_binding.png
download asset surface_binding.png 0.10 MB [opens in a new tab]
surface binding
Thumbnail image of SurfEneSI_v2.pdf
download asset SurfEneSI_v2.pdf 5 MB [opens in a new tab]
SurfEneSI v2