Seminaire du Prix Gay

Seminaire du Prix Gay-Lussac / Humboldt
à l'École Polytechnique
À l'occasion de la visite du Prof. Friedhelm Bechstedt au Laboratoire des Solides Irradiés, dans le cadre de son prix Gay Lussac/Humboldt 2008, nous serions très heureux de vous accueillir pour le séminaire :
Parameter-free calculations of solid-state excitations & spectra: fiction or reality?
Prof. Friedhelm Bechstedt
University of Jena and ETSF
The dream of computational physicists is to compute materials properties from
first principles without taking any parameter from experiment. The prize that has
to be paid in its realization is the inclusion of all important interactions between
nuclei and electrons in the investigated many-body systems. In the talk the
realization of the dream is illustrated for electronic excitations and related
measurable spectra. The progress in the field but also the limitations are discussed
for bulk oxides and nitrides which play an important role for electronics,
optoelectronics, and photovoltaics. Based on optimized atomic geometries charged
electronic excitations can be described within the quasiparticle approach with an
accuracy of about 0.1 eV. This holds not only for energy gaps but also for the
prediction of photoemission as well as X-ray absorption spectra.
The talk shows that the lineshape of optical spectra can indeed be predicted if
the electron-hole coupling is taken into account beyond the quasiparticle approach.
Examples are given not only for bulk systems but also for nanomaterials.
Vendredi 15 Mai 2009 - 10h30 - Amphi Bequerel
La rencontre se poursuivra autour d’un verre de champagne de 11h30 à 12h30.
Friedhelm Bechstedt et Lucia Reining seraient ravis de vous présenter lors de cet évènement l’infrastructure de recherche européenne qu’ils ont contribué à créer ensemble : l’European Theoretical Spectroscopy Facility ( http://www.etsf.eu ).