Regensburg 2002 – scientific programme

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SYOH: Organische Halbleiter

SYOH 7: Poster

SYOH 7.29: Poster

Monday, March 11, 2002, 18:00–21:00, C

Ab-initio theory of excitons in conjugated molecules and polymers — •Michael Rohlfing — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster

We investigate excitonic excitations and their optical spectra in π-conjugated molecules and polymers [1]. To this end, we employ parameter-free ab-initio techniques. Based on density-functional theory for the electronic ground state, the equations of motion for single-particle excitations (electron and hole states), as well as for coupled electron-hole excitations, are solved. Electronic many-body effects, like exchange and correlation, play a particular role. We discuss excitation states in conjugated molecules (e.g., polyenes, PTCDA, porphyrene) and in infinitely long polymer chains (poly-acetylene, PPV), which are dominated by bound exciton states. In addition to the transition energies of the excitations and their spectra, we investigate further properties of the excited states, like their spatial structure, singlet-triplet splitting, etc.

[1] M. Rohlfing and S.G. Louie, Phys. Rev. Lett. 82, 1959 (1999).