29.01.13 / 14:00

Science with Photons: A new first principles method for the calculation of transition metal L-edge spectra: theory and application

Veranstalter:	Helmholtz-Zentrum Berlin, Institut Methoden und Instrumentierung der Synchrotronstrahlung
Ort:	Albert-Einstein-Straße 15, 12489 Berlin
Raum:	BESSY-Hörsaal
Referent:	Prof. Dr. Frank Neese, Max-Planck Institut für Bioanorganische Chemie

A novel restricted open shell configuration interaction approach to the calculation of transition metal L-edges is introduced. The presented method is based on a Kohn-Sham density functional reference determinant for the entire molecular system (or cluster model) and accounts for spin-orbit coupling via quasi-degenerate perturbation theory. This procedure is the molecular equivalent of Russell-Saunders or LS coupling in atomic spectroscopy.

In the configuration interaction part of the approach a parameterization scheme with three parameters is used. These three parameters were obtained from optical spectroscopy and are universally applicable. Hence there are no disposable parameters that could be adjusted to fit experimental X-ray absorption spectra. Hence, the approach classifies as a predictive first-principles method rather than an analysis tool. A series of calculations on transition metal compounds is investigated and the results are compared in detail to experimental data. The series of investigated compounds comprises coordination compounds of copper, titanium, iron and nickel in various oxidation and spin states.

In most cases the approach yields good to excellent agreement with the experiment. Applications to the field of solid states and heterogneous catalysis will also be discussed.