Simulation of Spectral Profiles of B850–B800 Ring from LH2 Complex

Abstract

Light harvesting complexes from purple bacteria can be treated as relatively simple circular molecular systems. Absorption and steady state fluorescence spectra for such system are simulated. The spectra are calculated within full Hamiltonian model and compared for two types of fluctuations, that are modeled via uncorrelated static disorder. Gaussian fluctuations in local excitations energies and Gaussian fluctuations in positions of bacteriochlorophylls are considered. Dynamic disorder, interaction with phonon bath, is also taking into account for low and room temperature. The resulting spectra are presented and discussed for the model of the peripheral light harvesting complex LH2. Both rings (B850 ring and B800 one) are included in our model. Our results show strong dependence on temperature. Splitting of both spectra are visible only in low temperature. The differences caused by static disorder type are also remarkable.