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Issue 33, 2016
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van der Waals density functionals applied to corundum-type sesquioxides: bulk properties and adsorption of CH3 and C6H6 on (0001) surfaces

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Abstract

van der Waals (vdW) forces play an important role in the adsorption of molecules on the surface of solids. However, the choice of the most suitable vdW functional for different systems is an essential problem which must be addressed for different systems. The lack of a systematic study on the performance of the vdW functionals in the bulk and adsorption properties of metal-oxides motivated us to examine different vdW approaches and compute the bulk and molecular adsorption properties of α-Cr2O3, α-Fe2O3, and α-Al2O3. For the bulk properties, we compared our results for the heat of formation, cohesive energy, lattice parameters and bond distances between the different vdW functionals and available experimental data. Next we studied the adsorption of benzene and CH3 molecules on top of different oxide surfaces. We employed different approximations to exchange and correlation within DFT, namely, the Perdew–Burke–Ernzerhof (PBE) GGA, (PBE)+U, and vdW density functionals [DFT(vdW-DF/DF2/optPBE/optB86b/optB88)+U] as well as DFT-D2/D3(+U) methods of Grimme for the bulk calculations and optB86b-vdW(+U) and DFT-D2(+U) for the adsorption energy calculations. Our results highlight the importance of vdW interactions not only in the adsorption of molecules, but importantly also for the bulk properties. Although the vdW contribution in the adsorption of CH3 (as a chemisorption interaction) is less important compared to the adsorption of benzene (as a physisorption interaction), this contribution is not negligible. Also adsorption of benzene on ferryl/chromyl terminated surfaces shows an important chemisorption contribution in which the vdW interactions become less significant.

Graphical abstract: van der Waals density functionals applied to corundum-type sesquioxides: bulk properties and adsorption of CH3 and C6H6 on (0001) surfaces

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Publication details

The article was received on 15 Jan 2016, accepted on 18 Jul 2016 and first published on 27 Jul 2016


Article type: Paper
DOI: 10.1039/C6CP00346J
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2016,18, 23139-23146
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    van der Waals density functionals applied to corundum-type sesquioxides: bulk properties and adsorption of CH3 and C6H6 on (0001) surfaces

    S. Dabaghmanesh, E. C. Neyts and B. Partoens, Phys. Chem. Chem. Phys., 2016, 18, 23139
    DOI: 10.1039/C6CP00346J

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