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Bonding, charge rearrangement and interface dipoles of benzene, graphene, and PAH molecules on Au(111) and Cu(111)
Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-9402-1491
Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
2015 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 81, 620-628 p.Article in journal (Refereed) Published
Abstract [en]

We perform a theoretical study of the electronic properties of polyaromatic hydrocarbon (PAH) molecules, as well as benzene and graphene, adsorbed on copper and gold. The PAH molecules studied are coronene (C24H12), circumcoronene (C54H18) and circumcircumcoronene (C96H24), which we consider as gradual approximations to an infinite graphene layer. In order to understand how the size of the adsorbed PAH molecules influences the adsorbate-metal interactions, we generalize the approach used in our earlier study [Phys Rev B, 85 (2012), p. 205423] to decompose the binding energies and net charge transfers into separate contributions from specific groups of atoms, and we then show that the zigzag edges of the PAH molecules interact stronger with the metal surfaces than the armchair ones. We discuss the nature of binding in our model systems as well as the formation of interface dipoles. We show that for all model systems studied here, the charge rearrangement contribution to the interface dipoles can be expressed as the product of the charge involved in the formation of the dipole and the distance between well-defined centers of charge for electron accumulation and depletion. This distance is only marginally dependent on the specific PAH molecules, decreasing slowly with their size.

Place, publisher, year, edition, pages
Elsevier , 2015. Vol. 81, 620-628 p.
National Category
Physical Sciences
URN: urn:nbn:se:liu:diva-113164DOI: 10.1016/j.carbon.2014.09.096ISI: 000345682900066OAI: diva2:780357

Funding Agencies|Swedish Research Council (VR); Linkoping Linnaeus Initiative on Novel Functionalized Materials (VR); Swedish Foundation for Strategic Research (SSF) [RMA11-0029]; FunMat (Functional Nanoscale Materials) - a VINN Excellence Centre (Swedish Agency for Innovation Systems VINNOVA)

Available from: 2015-01-14 Created: 2015-01-12 Last updated: 2015-05-11
In thesis
1. Electronic properties of complex interfaces and nanostructures
Open this publication in new window or tab >>Electronic properties of complex interfaces and nanostructures
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis investigates the structural and electronic properties of graphene, polyaromatic hydrocarbon (PAH) molecules, and other carbon-based materials, when interacting with metallic surfaces, as well as under the influence of different types of perturbations. Density functional theory, incorporating van der Waals interactions, has been employed.

PAH molecules can, with gradual accuracy, be considered as approximations to an infinite graphene layer. A method to estimate the contributions to the binding energies and net charge transfers from different types of carbon atoms and CH groups in graphene- and PAH-metal systems has been generalized. In this extended method, the number and the nature of the functional groups is determined using a first-principles approach, rather than intuitively or through empirical considerations. Relationships between charge transfers, interface dipole moments and work functions in such systems are explored.

Although the electronic structure of physisorbed graphene keeps most of the features of freestanding graphene, the use of large supercells in calculations makes it difficult to resolve the changes introduced in the band structures of such materials. In this thesis, this was the initial motivation for the development of a method to perform the Brillouin zone unfolding of band structures. This method, as initially developed, is shown to be of general use for any periodic structure, and is even further generalized – through the introduction of the unfolding density operator – to tackle the unfolding of the eigenvalues of any arbitrary operator, with  both scalar as well as spinor eigenstates.

A combined experimental and theoretical investigation of the self-assembly of a binary mixture of 4,9-diaminoperylene-quinone-3,10-diimine (DPDI) and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) molecules on Ag(111) is presented. The DFT calculations performed here allow for the investigation of the interplay between molecule-molecule and molecule-surface interactions in the network.

Besides the main results mentioned above, this thesis also incorporates a study of silicon-metal nanostructures, as well as an investigation of the use of hybrid graphene-graphane structures as prototypes for atomically precise design in nanoelectronics.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. 80 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1668
National Category
Physical Sciences Condensed Matter Physics Atom and Molecular Physics and Optics
urn:nbn:se:liu:diva-117848 (URN)10.3384/diss.diva-117848 (DOI)978-91-7519-066-2 (print) (ISBN)
Public defence
2015-06-05, Nobel, Hus B, Campus Valla, Linköping, 09:00 (English)
Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2015-05-12Bibliographically approved

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