Theoretical Spectroscopy of Complex Chemical Systems
11:00 - 12:00
Christoph R. Jacob
Institute of Physical and Theoretical Chemistry, TU Braunschweig
CFEL (Bldg. 99)
Seminar Room I-II, EG.076-078
Quantum-chemical calculations are essential for the assignment and interpretation of spectra of small molecules as well as complex molecular systems. Large molecular systems present a significant challenge not only because of the increasing computational effort that is required for an accurate quantum-chemical description, but also require new approaches for the interpretation of the large amount of data provided by such calculations. On the other hand, small molecular systems with a complicated electronic structure, such as transition metal complexes, pose additional challenges and their theoretical spectroscopy also requires novel quantum-chemical approaches.
In my talk, I will outline some of our work concerning the theoretical spectroscopy of such complex chemical systems, focussing on the vibrational spectroscopy of biomolecules and on the X-ray spectroscopy of transition metal catalysts.
For vibrational spectroscopy, I will discuss how switching from the commonly used normal modes to localized modes can aid the interpretation of harmonic vibrational spectra  and how such localized modes can provide significant benefits in the calculation of anharmonic vibrational spectra . For X-ray spectroscopy, I will show how the combination with quantum-chemical calculations can provide insights into the electronic structure of transition metal complexes [3,4] and how it can help reveal the mechanism of the selective catalytic reduction of NO [5,6].
 Ch. R. Jacob, M. Reiher, J. Chem. Phys. 130 (2009), 084106.
 P. T. Panek, Ch. R. Jacob, ChemPhysChem 15, 3365 (2014).