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vdW FUNCTIONALS AND DISPERSION CORRECTIONS IMPROVE ACCURACY IN DFT CALCULATIONS OF A BIMETALLIC CATALYST
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.ORCID iD: 0000-0003-0816-2509
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.ORCID iD: 0000-0003-3570-0050
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.ORCID iD: 0000-0002-9842-4332
2019 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

There is high demand for versatile materials today, i.e. materials with flexible composition and tunable properties, but at the same time, affordable.  Nanoalloys, which can be tailored all the way down to the atomic scale, meet these requirements, and is expected to be a material class of great importance in many future technologies. One example is heterogeneous catalysis, where bimetallic nanoalloys have been used for long time to enhance catalytic processes, both when it comes to activity and selectivity for many chemical reactions.

The tailoring of nanoalloys at the atomic scale requires detailed knowledge of how the structure and the composition (and size and shape) affects the desired properties. Here, experiments alone are too obtuse to decipher the often very complex relation between atomic level structure and properties; theory have an important role to fill here.

The most popular theoretical methods used in materials science today is the density functional theory (DFT) [1].  The success of standard DFT to describe and predict bulk properties of metals and many complex alloys cannot be underestimated. However, for surfaces and nanoparticles, and some special alloys, the accuracy of the method is still questionable and here the lack of non-local correlation (dispersion) and inaccurate exchange description is believed to be the critical shortcomings. One way forward is therefore to improve upon these.

In this work, we focus on the Ni-Sn bimetallic alloys, which improves the selectivity in hydrogenation reactions.  For the Ni-Sn system, we have systematically investigated the capability of several DFT functionals which explicitly accounts for dispersion, either through an a posteriori correction (Grimme D3 corrections) [2], or by integrating it self-consistently into the functional (vdW class of functionals) [3]. We have both modelled bulk phases along with the most important surface structures, and compared how the different methods describes structural, energetic and electronic properties. We find that the inclusion of dispersion mainly affects the structural and energetic properties, leading to better agreement to experimental data. Interestingly, the improved structural description also gives slightly modified electronic properties, both in terms of the d-band levels, and work functions.  

Acknowledgements

This work was carried out with the financial support of the Swedish Research Council (VR), the Swedish Foundation for International Cooperation in Research and Higher Education, STINT, Åforsk foundation and by the Swedish national strategic e-Science program eSSENCE. The simulations were performed using computational resources provided by the Swedish National Infrastructure for Computing (SNIC) at HPC2N and PDC.

The authors are grateful to The Swedish Foundation for International Cooperation in Research and Higher Education, “Swedish Research Council” and and ÅForsk foundation for the financial support

References

[1] Klimes, J., Michaelides, A. J. Chem. Phys. 137, p 120901 (2012)

[2] Grimme, S., et. al., J. Chem. Phys. 132, p 154104 (2010)

[3] Berland, K, Hyldgaard, P., Phys. Rev. B, 89, p 035412 (2014)

Place, publisher, year, edition, pages
2019.
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-394006OAI: oai:DiVA.org:uu-394006DiVA, id: diva2:1356452
Conference
XXVIII International Materials Research Congress
Available from: 2019-10-01 Created: 2019-10-01 Last updated: 2019-10-01

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Kullgren, JollaBroqvist, Peter

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