Modeling Exciton Dynamics in Phycobiliproteins
Samuel Blau, Harvard University
Atomistic structures of two similar phycobiliproteins from different species of algae were recently obtained with protein crystallography. Although both function as efficient light harvesters, ultrafast spectroscopy reveals that only one exhibits oscillatory coherences attributed to quantum effects. Quantum coherence has been proposed as the mechanism for highly efficient energy transfer in photosynthetic systems; thus, comparing these two proteins can provide valuable insight into the importance of quantum effects in biology. We have investigated both compounds using an open quantum systems formalism. Atomistic spectral densities and system Hamiltonians were obtained from molecular dynamics and time-dependent density functional theory. With these in hand, hierarchical equations of motion were used to simulate non-Markovian exciton dynamics and predict spectra that can be directly compared with experimental results.
Abstract Author(s): Samuel M. Blau, Thomas Markovich, Christoph Kreisbeck, Alan Aspuru-Guzik