Cyclic molecular aggregates: influence of quasi-static and dynamic disorder on their excitonic line shapes

Abstract

For Frenkel excitons moving on molecular rings modeling in part bacteria photosynthetic antenna systems we investigate the influence of static and dynamic disorders on their optical line shape. The static disorder, describing inhomogeneities and slow motions of the protein backbone and the dynamic disorder, simulating the influence of vibrational degrees of freedom, are taken into account by fluctuations of the local excitation energies of the BChI molecules. The fluctuations are represented by dichotomic Markov processes with colored noise with different amplitudes and decay constants of the correlation functions. We obtain a closed set of equations of motion for the correlation functions determining the optical line shape which is solved numerically. We display the optical line shapes of the circular aggregates with 9 BChls for different regimes of the exciton transfer under the influence of the disorders and discuss them for various sets of the model parameters describing static and dynamic disorders.