Modified-scaled hierarchical equation of motion approach for the study of quantum coherence in photosynthetic complexes

TL;DR

This paper introduces a modified scaled hierarchical equation of motion approach that improves computational efficiency and accurately models quantum coherence in photosynthetic complexes, aligning well with experimental data.

Contribution

The paper develops and demonstrates a more efficient hierarchical method for simulating quantum coherence in photosynthetic systems, avoiding low-temperature corrections.

Findings

The modified approach reduces computational resources needed.

Time scales of coherence match experimental observations.

Population beating observed at physiological temperature.

Abstract

We present a detailed theoretical study of the transfer of electronic excitation energy through the Fenna-Matthews-Olson (FMO) pigment-protein complex, using the new developed modified scaled hierarchical approach [Shi Q. et al, J Chem Phys 2009, 130, 084105]. We show that this approach is computationally more efficient than the original hierarchical approach. The modified approach reduces the truncation levels of the auxiliary density operators and the correlation function. We provide a systematic study of how the number of auxiliary density operators and the higher-order correlation functions affect the exciton dynamics. The time scales of the coherent beating are consistent with experimental observations. Furthermore, our theoretical results exhibit population beating at physiological temperature. Additionally, the method does not require a low-temperature correction to obtain the correct thermal equilibrium at long times.