Nonlinear network model analysis of vibrational energy transfer and localisation in the Fenna-Matthews-Olson complex

摘要

Collective protein modes are expected to be important for facilitating energytransfer in the Fenna-Matthews-Olson (FMO) complex, however to date little workhas focussed on the microscopic details of these vibrations. The nonlinearnetwork model (NNM) provides a computationally inexpensive approach to studyingvibrational modes at the microscopic level, whilst incorporating anharmonicityin the inter-residue interactions which can influence protein dynamics. Weapply the NNM to the FMO complex and find evidence for the existence ofnonlinear discrete breather modes. These modes tend to transfer energy to thehighly connected core pigments, potentially opening up alternative excitationenergy transfer routes. Incorporating localised modes based on these discretebreathers in the optical spectra calculations for FMO using ab initio siteenergies and excitonic couplings can substantially improve their agreement withexperimental results.