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.