Effects of disorder on the optical properties of Frenkel excitons

The Coherent Potential Approximation (CPA) is used to study the effects of disorder on the absorption line shapes of Frenkel excitons in one-, two-, and three-dimensional systems. A Gaussian distribution of transition frequencies with rms width $\sigma $ was used. Several values of the disorder parameter $\sigma $. The CPA results show that short tails on the high-energy side of the peaks are $\sigma $ dependent, and long tails on the low-energy side of the peaks are independent of the disorder parameter $\sigma $.