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

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Theory of X-ray spectroscopy of strongly correlated systems
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

X-ray absorption spectroscopy measured at the L-edge of transition metals (TMs) is a powerful element-selective tool providing direct information about the correlation effects in the 3d states. The theoretical modelling of the 2p to 3d excitation processes remains a challenge for contemporary ab initio electronic structure techniques, due to strong core-hole and multiplet effects influencing the spectra. In this work we present a realisation of the method combining the density functional theory with multiplet ligand field theory, proposed in Phys. Rev. B 85, 165113 (2012). The core of this approach is the solution of the single-impurity Anderson model (SIAM), parameterised from first principles.In our implementation, we adopt  the dynamical mean-field theory and utilize the local Hamiltonian and the hybridisation function, projected onto TM 3d states, in order to construct the SIAM. We show that the current method can be used as an alternative to the construction of the Wannier functions. The developed computational scheme is applied to calculate the L-edge spectra for several TM monoxides. An excellent agreement between the theory and experiment is found for all studied systems. The possible extensions of the method as well as its limitations are discussed.

National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-281570OAI: oai:DiVA.org:uu-281570DiVA, id: diva2:914623
Available from: 2016-03-24 Created: 2016-03-24 Last updated: 2016-04-29
In thesis
1. Complex Excitations in Advanced Functional Materials
Open this publication in new window or tab >>Complex Excitations in Advanced Functional Materials
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Understanding the fundamental electronic properties of materials is a key step to develop innovations in many fields of technology. For example, this has allowed to design molecular based devices like organic field effect transistors, organic solar cells and molecular switches.

In this thesis, the properties of advanced functional materials, in particular metal-organic molecules and molecular building blocks of 2D materials, are investigated by means of Density Functional Theory (DFT), the GW approximation (GWA) and the Bethe-Salpeter equation (BSE), also in conjunction with experimental studies. The main focus is on calculations aiming to understand spectroscopic results.

In detail, the molecular architectures of lutetium-bis-phthalocyanine (LuPc2) on clean and hydrogenated vicinal Si(100)2×1, and of the biphenylene molecule on Cu(111) were analysed by means of X-ray Photoelectron spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy; DFT calculations were performed to obtain insights into the atomic and electronic structures. Furthermore, detailed information about the electronic states of the gas phase iron phthalocyanine (FePc) and of the gas phase biphenylene molecule were obtained through XPS and NEXAFS spectroscopy. I have studied by means of DFT, multiplet and GWA calculations the electronic correlation effects in these systems. Also the optical, electronic and excitonic properties of a hypothetical 2D material based on the biphenylene molecule were investigated by GWA and BSE calculations. Monolayers of metal-free phthalocyanine (H2Pc) on Au(111) and of FePc on Au(111) and Cu(100)c(2×2)-2N/Cu(111) with and without pyridine modifier were studied by XPS and final state calculations. A multiplet approach to compute L-edges employing the hybridizations function, known from dynamical mean field theory, was proposed and applied to transition metal oxides.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. p. 90
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1365
Keywords
X-ray Absorption Spectroscopy, Photoelectron Spectroscopy, Adsorption, Phthalocyanines, Biphenylene, Excitons, Functional Materials
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-282151 (URN)978-91-554-9543-5 (ISBN)
Public defence
2016-05-13, Å80101, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2016-04-22 Created: 2016-04-03 Last updated: 2016-04-29

Open Access in DiVA

No full text in DiVA

Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 354 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf