Optical absorption and delocalization in a quaternary tight-binding chain with correlated disorder

We study electronic transport in a one-dimensional model with four kinds of atoms. The quaternary energy distribution is chosen in such a way that it contains long-range correlations. Localization properties and optical absorption are obtained by using numerical methods. Regarding the localization properties of the wave function, we show numerically that, for weak correlation on disorder, the participation number is finite, and the eigenstates are localized. For strong correlation, our results suggest that the model displays fully delocalized eigenstates. Weakly localized states are present in the regime of intermediate correlations. Our analysis of the optical absorption showed an interesting pattern of peaks and a strong dependence on the correlation degree. The structure of peaks is discussed in the light of the underlying density of states.