Decoherence in Weakly Coupled Excitonic Complexes

TL;DR

This paper derives equations of motion for weakly coupled excitonic complexes that incorporate decoherence effects, enabling better understanding of energy transfer and spectral features in such systems.

Contribution

It introduces a new theoretical framework that accounts for decoherence in excitonic complexes while maintaining a basis of localized electronic states.

Findings

Equations relate to Foerster energy transfer but include decoherence effects.

Calculated spectra show delocalization and coupling reduction due to bath interactions.

Demonstrates the impact of decoherence on optical spectra in model systems.

Abstract

Equations of motion for weakly coupled excitonic complexes are derived. The description allows to treat the system in the basis of electronic states localized on individual chromophores, while at the same time accounting for experimentally observable delocalization effects in optical spectra. The equations are show to be related to the well-known Foerster type energy transfer rate equations, but unlike Foerster equations, they provide a description of the decoherence processes leading to suppression of the resonance coupling by bath fluctuations. Linear absorption and two-dimensional photon echo correlation spectra are calculated for simple model systems in homogeneous limit demonstrating distinct delocalization effect and reduction of the resonance coupling due to interaction with the bath.