Coherence effects in ring molecular systems

Abstract

AbstractThe time dependence of the occupation probability decay of optically allowed states in molecular rings (resembling the B850 ring of the purple bacterium Rhodopseudomonas acidophila ‐ nonameric symmetry ‐ and Rhodopseudomonas palustris ‐ octameric symmetry) is calculated. The dipole moments are arranged tangentially in nonameric ring and radially in octameric ring. Fast fluctuations of the environment are simulated by dynamic disorder and slow fluctuations by static disorder. In the present investigation we are comparing results for the time development of the occupation probabilities of optically allowed exciton states P k =±1 (nonameric ring) and P k =±7 (octameric ring) for four models of static disorder: Gaussian disorder in the local energies (Model A), Gaussian disorder in the transfer integrals (Model B), Gaussian disorder in radial positions of molecules (Model C) and Gaussian disorder in angular positions of molecules (Model D). Both types of disorder ‐ static and dynamic ‐ are taken into account simultaneously. We have used Markovian and non‐Markovian treatment of the interaction with the bath. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)