96 research outputs found
Bloch-Redfield equations for modeling light-harvesting complexes
We challenge the misconception that Bloch-Redfield equations are a less
powerful tool than phenomenological Lindblad equations for modeling exciton
transport in photosynthetic complexes. This view predominantly originates from
an indiscriminate use of the secular approximation. We provide a detailed
description of how to model both coherent oscillations and several types of
noise, giving explicit examples. All issues with non-positivity are overcome by
a consistent straightforward physical noise model. Herein also lies the
strength of the Bloch-Redfield approach because it facilitates the analysis of
noise-effects by linking them back to physical parameters of the noise
environment. This includes temporal and spatial correlations and the strength
and type of interaction between the noise and the system of interest. Finally
we analyze a prototypical dimer system as well as a 7-site Fenna-Matthews-Olson
(FMO) complex in regards to spatial correlation length of the noise, noise
strength, temperature and their connection to the transfer time and transfer
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