Berlin 2005 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 51: Einstein Symposium Brownian Motion, Diffusion and Beyond (SYBM) – Contributed Talks II

DY 51.7: Vortrag

Mittwoch, 9. März 2005, 11:45–12:00, TU H2032

A paradox of non-Markovian dynamic disorder — •Igor Goychuk — Institut für Physik, Universität Augsburg, Germany

Rate processes with fluctuating rates are ubiquitous in nature. For example, a nonadiabatic donor-acceptor electron transfer (ET) in some proteins can be strongly influenced by the conformational jump dynamics between two macroconformations of the electron-transferring protein possessing two very different ET rates. The conformational dynamics will introduce a sort of stochastic time-dependence into the ET rates. This situation is known under the label of dynamic disorder. If the rate fluctuations are very fast on the time-scale of electron transfer, i.e. the mean residence times spent in the protein macroconformations are much less than the inverse of corresponding ET rates, a self-averaging occurs and the ET kinetics is described by the averaged ET rate. This is the fast fluctuation limit. In the opposite limit of quasi-static disorder, the averaged transfer kinetics is described by a weighted average of the two exponentials with the ET rates reflecting temporally “frozen" conformations. This picture is well established in the case of Markovian dynamic disorder which is characterized by the exponential distributions of the conformational residence times. I will show that the influence of non-Markovian dynamic disorder characterized by a broad distribution of the residence times can be highly nontrivial. A fast fluctuation limit, in accordance with the Markovian criteria, may surprisingly reveal a quasi-static rate distribution in the averaged dynamics. A clear-cut resolution of this apparent paradox will be provided and its practical consequences will be discussed.