Group Members

  • Ulrich Wedig

Research

Electronic structure and the chemical bond

We investigate the structure and properties of molecules and solids using quantum-theoretical methods. Besides procedures based on the density functional theory (DFT), wavefunction based methods are applied, especially to treat dynamical electron correlation more accurately. For compounds containing heavy elements, the impact of the theory of relativity on the electronic structure is taken into account.

The quantum-mechanical results have to be related to chemical concepts of charges and bonding, which are often heuristic in nature. In order to accomplish this purpose, tools like the topological analysis of the electron density or the electron localization function (ELF) are used.

 

See also: Intermetallic phases

Examples

Investigations of the anisotropic hcp structures of elemental Zn and Cd:
Calculations with the method of increments (CCSD(T)) show, that the bonding in Zn and Cd
is due to dynamical electron correlation with a substantial contribution of the filled d-shell.
The various shapes of the [Tl8]6- clusteranion are derived from an ideal cube by displacive
distortions. A closed-shell electronic system is either obtained by spin-orbit coupling or by
Jahn-Teller distortion.
In recent high-pressure and high-temperature experiments new polymorphs of Bi2O3 were
found. HP-Bi2O3 exhibits two Bi sites with different stereo-chemical activity of the lone electron
pairs. The orientation of the lone pairs suggests ferroelectric behaviour.

Topics and related publications:

Chemical concepts and quantum chemistry

  • M. Jansen, U.Wedig:
    Das Teil im Ganzen – Missverständnisse um chemische Konzepte
    A Piece of the Picture – Misunderstanding of Chemical Concepts
    Angewandte Chemie 120 (2008) 10176-10180
    Angewandte Chemie Int. Ed. 47 (2008) 10026-10029 doi:10.1002/anie.200803605

Metallic elements and intermetallic compounds: Local bonding and dynamical correlation

  • J. Nuss, U. Wedig, M. Jansen: Geometric Variations and Electron Localizations in Intermetallics: The Case of La2Sb Type Compounds
    Z. Anorg. Allg. Chem. 637 (2011) 1975-1981 doi:10.1002/zaac.201100331
  • J. Nuss, U. Wedig, M. Jansen: Synthesis, Structure, and Properties of Scandium Dysprosium Antimonide ScDySb
    Zeitschrift für Anorganische und Allgemeine Chemie, 636 (2010) 913-918 doi:10.1002/zaac.201000095
  • J. Nuss, U. Wedig, A. Kirfel, M. Jansen: The Structural Anomaly of Zinc: Evolution of Lattice Constants and Parameters of Thermal Motion in the Temperature Range of 40 to 500 K
    Zeitschrift für Anorganische und Allgemeine Chemie, 636 (2010) 309-313 doi:10.1002/zaac.200900460
  • N. Gaston, D. Andrae, B. Paulus, U. Wedig, M. Jansen: Understanding the hcp Anisotropy in Cd and Zn: The Role of Electron Correlation in Determining the Potential Energy Surface
    Physical Chemistry Chemical Physics 12 (2010) 681-687 doi:10.1039/b915967c
  • N. Gaston, B. Paulus, U. Wedig, M. Jansen: Multiple Minima on the Energy Landscape of Elemental Zinc: A Wave Function Based Ab Initio Study
    Physical Review Letter 100 (2008) 226404-1-4 doi:10.1103/PhysRevLett.100.226404
  • U. Wedig, M. Jansen, B. Paulus, K. Rosciszewski, P. Sony: Structural and electronic properties of Mg, Zn and Cd from Hartree-Fock and density functional calculations including hybrid functionals
    Physical Review B 75 (2007) 205123-1-9 doi:10.1103/PhysRevB.75.205123
  • Y. Grin, F. R. Wagner, M. Armbrüster, M. Kohout, A. Leithe-Jasper, U. Schwarz, U. Wedig, H. G. von Schnering: CuAl2 revisited: Composition, crystal structure, chemical bonding, compressibility and Raman spectroscopy
    Journal of Solid State Chemistry 179 (2006) 1707 – 1719 doi:10.1016/j.jssc.2006.03.006
  • J. Nuss, U. Wedig, M. Jansen: Geometric variations and electron localizations in intermetallics: PbFCl type compounds
    Zeitschrift für Kristallographie 221 (2006) 554 – 562 doi:10.1524/zkri.2006.221.5-7.554

Compounds of heavy elements: The impact of the theory of relativity

  • V. Saltykov, J. Nuss, U. Wedig, Dasari L. V. K. Prasad, M. Jansen: First Isolated “Hypoelectronic” [In6]6- Cluster in Insulating Cs22In6(SiO4)4
    Z. Anorg. Allg. Chem. 637 (2011) 834-839 doi:10.1002/zaac.201100074
  • V. Saltykov, J. Nuss, U. Wedig, M. Jansen: Regular [Tl6]6- Cluster in Cs4Tl2O Exhibiting Closed-Shell Configuration and Energetic Stabilization due to Relativistic Spin-Orbit Coupling
    Z. Anorg. Allg. Chem. 637 (2011) 357-361 doi:10.1002/zaac.201000405
  • U. Wedig, V. Saltykov, J. Nuss, M. Jansen: Homoatomic Stella Quadrangula [Tl8]6- in Cs18Tl8O6, Interplay of Spin-Orbit Coupling, and Jahn-Teller Distortion
    Journal of the American Chemical Society, 132 (2010) 12458-12463 doi:10.1021/ja1051022
  • A. Karpov, U. Wedig, R. E. Dinnebier, M. Jansen: Dibariumplatinide: (Ba2+)2Pt2-•2e- and its Relation to the Alkaline-Earth-Metal Subnitrides
    Angewandte Chemie, 117 (2005) 780 – 783
    Angewandte Chemie Int. Ed. 44 (2005) 770 – 773 doi:10.1002/anie.200462055
  • A. Karpov, J. Nuss, U. Wedig, M. Jansen: Covalently Bonded 1∞[Pt]--Chains in BaPt: Extension of the Zintl-Klemm Concept to Anionic Transition Metals?
    Journal of the American Chemical Society, 126 (2004) 14123 – 14128 doi:10.1021/ja0401186
  • A. Karpov, J. Nuss, U. Wedig, M. Jansen:
    Cs2Pt, ein Platinid(-II) mit vollständiger Ladungstrennung
    Cs2Pt: A Platinide(-II) Exhibiting Complete Charge Separation
    Angewandte Chemie 115 (2003) 4966 – 4969
    Angewandte Chemie Int. Ed. 42 (2003) 4818 – 4821 doi:10.1002/anie.200352314

Oxides and Nitrides: Chemical bonding and ordering phenomena

  • J. Nuss, U. Wedig, M. Jansen: Structural Ordering Principles in Quasi One-Dimensional Wigner Crystals of the Series Na1+xCuO2 (0 ≤ x ≤ 1)
    Z. Kristallogr. 226 (2011) 627-632 doi:10.1524/zkri.2011.1402
  • T. Locherer, Dasari L. V. K. Prasad, R. Dinnebier, U. Wedig, M. Jansen, G. Garbarino, T. Hansen: High-Pressure Structural Evolution of HP-Bi2O3
    Phys. Rev. B, 83 (2011) 214102-1-12 doi:10.1103/PhysRevB.83.214102
  • S. Ghedia, T. Locherer, R. Dinnebier, D. L. V. K. Prasad, U. Wedig, M. Jansen, A. Senyshyn: High-pressure and high-temperature multianvil synthesis of metastable polymorphs of Bi2O3: Crystal structure and electronic properties
    Physical Review B, 82 (2010) 024106-1-12 doi:10.1103/PhysRevB.82.024106
  • C. L. Schmidt, U. Wedig, R. Dinnebier, M. Jansen: Synthesis, Crystal Structure, Bonding, and Properties of (Ba6O)(OsN3)2
    Chemistry - An Asian Journal 3 (2008) 1983 – 1990 doi:10.1002/asia.200800232
  • U. Wedig, P. Adler, J. Nuss, H. Modrow, M. Jansen: Studies on the electronic structure of Ag2NiO2, an intercalated delafossite containing subvalent silver.
    Solid State Sciences 8 (2006) 753 – 763 doi:10.1016/j.solidstatesciences.2006.04.004

Fullerenes and Fullerides

  • A. Reich, M. Panthöfer, H. Modrow, U. Wedig, M. Jansen: The Structure of Ba@C74
    Journal of the American Chemical Society, 126 (2004) 14428 – 14434 doi:10.1021/ja0401693
  • U. Wedig, H. Brumm, M. Jansen: Synthesis, Characterization, and Bonding Properties of Polymeric Fullerides AC70•nNH3 (A = Ca, Sr, Ba, Eu, Yb).
    Chemistry, A European Journal 8 (2002) 2769 – 2774
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