Influence of pigment-protein coupling on excitation energy transfer in FMO complex

TL;DR

This study investigates how inhomogeneous pigment-protein couplings affect excitation energy transfer in the FMO complex, revealing that asymmetry in couplings can explain experimental oscillatory dynamics.

Contribution

The paper introduces a model with site-specific pigment-protein couplings, demonstrating their role in energy transfer dynamics and oscillation preservation in the FMO complex.

Findings

Asymmetric couplings align with experimental oscillation data

Correlated fluctuations help maintain long-term oscillations

Different BChla sites exhibit varied oscillation time-scales

Abstract

To explain experimentally observed oscillatory dynamics of highly efficient process of excitation energy transfer (EET) in Fenna-Matthews-Olson (FMO) complex, most theoretical models assume the same local protein environment around all the bacteriochlorophyll-a (BChla) sites, contradictory to the structural analysis of FMO complex. Using different values of pigment-protein couplings for different BChla sites, measured in the adiabatic limit of electron transfer, we theoretically investigate the effect of inhomogeneous local protein environment on excitation energy transfer. By employing non-Markovian master equation we demonstrate that the asymmetric system-bath coupling leads to the results consistent with the experimental observations. Quantum dynamical simulation suggests that the correlated fuctuations preserve the oscillation of excitation for long time-scales. Further different BChla sites have asymmetric time-scales of oscillations of excitation due to in-homogeneous pigment-protein couplings also.