Comment on "Excitons in Molecular Aggregates with Levy Disorder:   Anomalous Localization and Exchange Broadening of Optical Spectra"
  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. 
Agnieszka Werpachowska (UCL) and Alexandra Olaya-Castro
cond-mat.dis-nn cond-mat.mes-hall quant-ph