Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.99: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

excited states of the chromophores within many-body perturbation theory — •yuchen ma and michael rohlfing — Fachbereich Physik, Universität Osnabrück, Germany

Although the chromophores of photoactive yellow proteins and rhodopsin proteins have been the subject of numerous spectroscopic investigations because of their unique biochemistry and photophysical properties, the position in energy of their excited states are still not well-defined in theory. We use the ab-initio many-body perturbation theory (GW approximation and Bethe-Salpeter equation) to study the excited states of these chromophores, which taking into account electronic exchange, correlation, and electron-hole interaction effects.

Calculations show that the resonant-antiresonant coupling beyond the commonly employed Tamm-Dancoff approximation is needed for an accurate description of the lowest π→π^∗ excitations, which affects the excitation energy by up to 0.4 eV. The huge exchange interaction between the electron and hole leads to the unnegligible coupling between the resonant transition and the antiresonant counterpart. The lowest n→π^∗ excitation for the chromophores of photoactive yellow proteins is composed from free electron-hole transitions with very different quasiparticle transition energies. An accurate description of the lowest n→π^∗ excitation requires inclusion of the dynamics effect in the electron-hole screening, which affects the excitation energy by up to 0.3 eV.