Energy flow in the Photosystem I supercomplex: comparison of approximative theories with DM-HEOM

TL;DR

This paper investigates exciton dynamics in Photosystem I using DM-HEOM, comparing exact and approximate theories to validate transfer times and spectral properties against experimental data.

Contribution

It introduces a detailed DM-HEOM analysis of Photosystem I and evaluates the accuracy of approximate theories for exciton transfer.

Findings

DM-HEOM provides accurate exciton transfer times.

Approximate theories show deviations from exact results.

Spectral calculations align well with experimental data.

Abstract

We analyze the exciton dynamics in PhotosystemI from Thermosynechococcus elongatus using the distributed memory implementation of the hierarchical equation of motion (DM-HEOM) for the 96 Chlorophylls in the monomeric unit. The exciton-system parameters are taken from a first principles calculation. A comparison of the exact results with Foerster rates and Markovian approximations allows one to validate the exciton transfer times within the complex and to identify deviations from approximative theories. We show the optical absorption, linear, and circular dichroism spectra obtained with DM-HEOM and compare them to experimental results.