Dissipative Exciton Transfer in Donor-Bridge-Acceptor Systems: Numerical Renormalization Group Calculation of Equilibrium Properties

TL;DR

This paper models exciton transfer in donor-bridge-acceptor systems considering Coulomb interactions and environmental dissipation, using numerical renormalization group to analyze phase transitions and spectral properties.

Contribution

It introduces a non-perturbative NRG approach to study equilibrium properties of DBA systems with strong Coulomb and environmental couplings.

Findings

Identifies a transition to localized exciton states depending on dissipation strength.

Provides phase diagrams and absorption spectra for systems up to six sites.

Highlights criteria favoring delocalized exciton transfer.

Abstract

We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.