uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Large-scale SCC-DFTB calculations of reconstructed polar ZnO surfaces
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
Show others and affiliations
2014 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 628, 50-61 p.Article in journal (Refereed) Published
Abstract [en]

We present a theoretical study of a range of surface defects for the most abundant polar ZnO(0001)/(000 (1) over bar) surfaces using a tight binding approach with self-consistent charges (SCC-DFTB). We find that a combination of triangular pits at the Zn-terminated surface and a strongly ordered hexagonal defect pattern at the O-terminated surface constitutes a very stable reconstruction, in excellent agreement with experimental findings. On the whole, the SCC-DFTB method describes the polar surfaces of ZnO very well, and at a low computational cost which allows for the investigation of larger - and more realistic - surface structures compared to previous studies. Such large-scale calculations show that, at the Zn-terminated surface, the reconstruction results in a high density of one-layer deep triangular pit-like defects and surface vacancies which allow for a high configurational freedom and a vast variety of defect motifs. We also present extensive tests of the performance of the SCC-DFTB method in comparison with DFT results.

Place, publisher, year, edition, pages
2014. Vol. 628, 50-61 p.
Keyword [en]
ZnO, Polar surfaces, SCC-DFTB, DFT
National Category
Condensed Matter Physics Chemical Sciences
URN: urn:nbn:se:uu:diva-230913DOI: 10.1016/j.susc.2014.05.001ISI: 000340221200008OAI: oai:DiVA.org:uu-230913DiVA: diva2:743874
Available from: 2014-09-05 Created: 2014-09-01 Last updated: 2015-01-14Bibliographically approved
In thesis
1. Chemistry and Physics of Cu and H2O on ZnO Surfaces: Electron Transfer, Surface Triangles, and Theory
Open this publication in new window or tab >>Chemistry and Physics of Cu and H2O on ZnO Surfaces: Electron Transfer, Surface Triangles, and Theory
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis discusses the chemistry and physics of Cu and H2O on ZnO surfaces, based primarily on results from quantum chemical calculations. The underlying context is heterogeneous catalysis, where Cu/ZnO-mixtures are used in the industrial synthesis of methanol and in the water gas shift reaction. Electron transfer between small Cu clusters and ZnO is central to this thesis, as are the design and use of models that can describe realistic and very large-scale ZnO surface structures while still retaining the electronic nature of the system. Method and model enhancements as well as tests and validations constitute a large part of this thesis.

The thesis demonstrates that the charges of small Cu clusters, adsorbed on the non-polar ZnO(10-10) surface, depend on whether the Cu clusters contain an even or odd number of atoms, and whether water is present (water can induce electron transfer from Cu to ZnO). On the polar Zn-terminated ZnO(0001) surface, Cu becomes negatively charged, which causes it to attract positively charged subsurface defects and to wet the ZnO(0001) surface at elevated temperatures.

When a Cu cluster on a ZnO surface becomes positively charged, this happens because it donates an electron to the ZnO conduction band. Hence, it is necessary to use a method which describes the ZnO band gap correctly, and we show that a hybrid density functional, which includes a fraction of Hartree-Fock exchange, fulfills this requirement. When the ZnO conduction band becomes populated by electrons from Cu, band-filling occurs, which affects the adsorption energy. The band-filling correction is presented as a means to extrapolate the calculated adsorption energy under periodic boundary conditions to the zero coverage (isolated adsorbate, infinite supercell) limit.

A part of this thesis concerns the parameterization of the computationally very efficient SCC-DFTB method (density functional based tight binding with self-consistent charges), in a multi-scale modeling approach. Our findings suggest that the SCC-DFTB method satisfactorily describes the interaction between ZnO surfaces and water, as well as the stabilities of different surface reconstructions (such as triangularly and hexagonally shaped pits) at the polar ZnO(0001) and ZnO(000-1) surfaces.


Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 50 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1207
catalysis, density functional theory, SCC-DFTB, band-filling correction
National Category
Chemical Sciences
urn:nbn:se:uu:diva-236302 (URN)978-91-554-9111-6 (ISBN)
Public defence
2015-01-09, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2014-12-18 Created: 2014-11-17 Last updated: 2015-02-03

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hellström, MattiHermansson, KerstiBroqvist, Peter
By organisation
Department of Chemistry - ÅngströmStructural Chemistry
In the same journal
Surface Science
Condensed Matter PhysicsChemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 424 hits
ReferencesLink to record
Permanent link

Direct link