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CPP: Chemische Physik und Polymerphysik

CPP 12: POSTER Colloids, Nanoparticles and Self-Organizing Systems

CPP 12.27: Poster

Dienstag, 28. März 2006, 17:00–19:00, P3

Absorption spectra for light-harvesting systems using non-Markovian as well as modified Redfield master equations — •M. Schröder, M. Schreiber, and U. Kleinekathöfer — Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz

Circular aggregates are studied to model the B850 ring of bacteriochlorophylls within the LH2 complex of purple bacteria. The spectral density which describes the coupling strength and frequency dependence of the interaction between the ring system and the environment has recently been determined by ab initio calculations [1]. Starting with a quantum master equation one can develop a formula for the frequency-domain absorption spectra [2]. Often one decouples the population dynamics from that of the coherences (secular approximation) and neglects memory effects (Markov approximation) in this procedure. Here we will investigate these approximations in some more detail as well as the influence of the form of the spectral density and static disorder using Monte Carlo methods. The calculations will be made using a numerical decomposition of the spectral density and different formalisms to treat the memory effects: time-local and time-nonlocal approaches as well as the modified Redfield method [3].

[1] A. Damjanović, I. Kosztin, U. Kleinekathöfer, and K. Schulten, Phys. Rev. E 65, 031919 (2002).

[2] F. Neugebauer, D. Malzahn, and V. May, Chem. Phys. 201, 151 (1995).

[3] W.M. Zhang, T. Meier, V. Chernyak, S. Mukamel, J. Chem. Phys. 108, 7763 (1998)