People: Prof. Ulrich Kleinekathöfer, Sayan Maity
The light absorption in light-harvesting complexes is mainly performed by chlorophyll or bilin molecules. Experimental findings in some of these complexes suggest the existence of long-lived coherences between the individual pigments at low temperatures . In this context the question arises if the bath-induced fluctuations at different chromophores are spatially correlated or not. To this end we are performing classical molecular dynamics simulations and quantum chemistry calculations on some light-harvesting systems. In these investigations at different temperatures, only weak correlations between the movements of the chromophores were detected. Furthermore two strategies are followed how to use the input from the atomistic simulations to study the transfer of energy in light-harvesting systems. On the one hand, spectral densities are being determined and density matrix calculations performed. On the other hand, the time-dependent Hamiltonians are directly employed in wave-packet based Ehrenfest calculations. On top of this, the same techniques can be employed to determine two-dimensional spectra which can be directly linked to experiment.
Please see also the webpage on FMO excitation dynamics.
 M. I. Mallus, M. Schallwig and U. Kleinekathöfer, Relation between Vibrational Dephasing Time and Energy Gap Fluctuations, J. Phys. Chem. B 121, 6471–6478 (2017).
 M. I. Mallus, M. Aghtar, S. Chandrasekaran, G. Lüdemann, M. Elstner and U. Kleinekathöfer, Relation between Dephasing Time and Energy Gap Fluctuations in Biomolecular Systems, J. Phys. Chem. Lett. 7, 1102–1108 (2016).
 S. Chandrasekaran, M. Aghtar, S. Valleau, A. Aspuru-Guzik and U. Kleinekathöfer, Influence of Force Fields and Quantum Chemistry Approach on Spectral Densities of BChl a in Solution and in FMO Proteins, J. Phys. Chem. B 119, 9995-10004 (2015).
 M. Aghtar, J. Strümpfer, C. Olbrich, K. Schulten and U. Kleinekathöfer, Different Types of Vibrations Interacting with Electronic Excitations in Phycoerythrin 545 and Fenna-Matthews-Olson Antenna Systems, J. Phys. Chem. Lett. 5, 3131–3137 (2014).
 C. Olbrich, J. Strümpfer, K. Schulten and U. Kleinekathöfer, Theory and Simulation of the Environmental Effects on FMO Electronic Transitions, J. Phys. Chem. Lett. 2, 1771–1776 (2011).
 C. Olbrich, T. L. C. Jansen, J. Liebers, M. Aghtar, J. Strümpfer, K. Schulten, J. Knoester and U. Kleinekathöfer, From Atomistic Modeling to Excitation Dynamics and Two-dimensional Spectra of the FMO Light-harvesting Complex, J. Phys. Chem. B 115, 8609–8621 (2011).
 C. Olbrich, J. Strümpfer, K. Schulten and U. Kleinekathöfer, Quest for Spatially Correlated Fluctuations in the FMO Light-harvesting Complex, J. Phys. Chem. B 115, 758–764 (2011).
 C. Olbrich and U. Kleinekathöfer, Time-dependent Atomistic View on the Electronic Relaxation in Light-harvesting System II, J. Phys. Chem. B 114, 12 427–12 437 (2010).