Electron localization in a two-channel tight-binding model with correlated disorder

We calculate the localization length in a two-channel tight-binding model for correlated disordered site potential. Both intra- and interchannel correlations are taken into account. The localization length is obtained in quadratic approximation by expanding the two-channel conductance over weak disorder. The result is applied to a simple two-stranded model of DNA molecule and it is shown that a strong pair coupling between the basic nucleotides in the strands is not sufficient to delocalize electronic states.

Figure 1

The localization length vs energy. Solid line is for the uncorrelated (white noise) potential. Dashed-dotted line is for exponential intra- and interchannel correlation functions; all three are given by Eq. (34). Dotted line is for exponential intrachannel correlations and delta-correlated interchannel scattering. The parameters of the model are $h=0.5\mathrm{eV}$, $t=1.0\mathrm{eV}$, and $⟨{\epsilon }_1^2⟩=⟨{\epsilon }_2^2⟩=⟨{\epsilon }_{12}^2⟩={0.25}^2$.