Structure-Dynamics Relation in Physically-Plausible Multi-Chromophore Systems

We study a large number of physically-plausible arrangements of chromophores, generated via a computational method involving stochastic real-space transformations of a naturally-occurring “reference” structure, illustrating our methodology using the well-studied Fenna–Matthews–Olson complex (FMO). To explore the idea that the natural structure has been tuned for efficient energy transport, we use an atomic transition charge method to calculate the excitonic couplings of each generated structure and a Lindblad master equation to study the quantum transport of an exciton from a “source” to a “drain” chromophore. We find significant correlations between structure and transport efficiency: High-performing structures tend to be more compact and, among those, the best structures display a certain orientation of the chromophores, particularly the chromophore closest to the source-to-drain vector. We conclude that, subject to reasonable, physically motivated constraints, the FMO complex is highly attuned to the purpose of energy transport, partly by exploiting these structural motifs.