Absorption spectrum of a one-dimensional chain with Frenkel's exciton   under diagonal disorder represented by hyperbolic defects
  A method is proposed for calculating the absorption spectrum of a long one-dimensional closed-into-a-ring chain with Frenkel's exciton under diagonal disorder. This disorder is represented by the hyperbolic singularities of atomic fission. These defects are shown to lead to a wing in the exciton zone of a chain without defects. The form of the wing does not depend on the relative positions or number of defects and its value is proportional to the sum of the amplitudes of the defects. The proposed method uses only the continual approximation. 
G. G. Kozlov