Comment on "Excitons in Molecular Aggregates with Levy Disorder: Anomalous Localization and Exchange Broadening of Optical Spectra"

TL;DR

This paper critiques a previous study on exciton behavior in Levy-disordered molecular aggregates, arguing that existing theories sufficiently explain the observed phenomena without requiring new models.

Contribution

It clarifies that the earlier theoretical framework remains valid and does not need revision to account for the reported exchange broadening and localization effects.

Findings

Existing theory explains the observed exchange broadening.

No need for new models to describe exciton localization.

Previous predictions remain consistent with recent observations.

Abstract

In their Letter [Phys. Rev. Lett. 105, 137402 (2010)], Eisfeld et al. predicted the exchange broadening and blue-shift of the absorption band as well as a nonuniversal disorder scaling of the localization length of excitons in J-aggregates with Levy disorder, which they contrasted with the previously analyzed Gaussian and Lorentzian case [Phys. Rev. B, 79, 1 (2009)]. The observations were explained by chain segmentation due to outliers, and its interplay with localization of states in effective potential wells created by typical random site energies. We argue that the previously known theory does not break down and thus anticipates the properties of absorption band investigated in the commented work.