Absorption line shape of Frenkel excitons in one-dimensional random chains with pairwise correlated Gaussian disorder Original Research Article

We investigate inhomogeneous broadening of absorption line shapes of an ensemble of linear Frenkel chains with a Gaussian distribution of molecular transition energies. Two models of Gaussian disorder are considered. In one case, the molecular energies are uncorrelated variables whereas in the second model the molecular energies are pairwise correlated. A perturbative treatment in the disorder is used to determine that the broadening is larger in the presence of correlations. In the case of nonperturbative magnitudes of disorder, we find a good agreement of the theoretical treatment with numerical simulations, when the number of molecules in the system is replaced by the number of coherently bound molecules.