Crossover between localization and delocalization in a random non-integer n-mer chain

摘要

We study in this paper numerically the nature of the electronic states in a random system with impurities constituted by dimers and monomers having the same potential strength. The combination of these two impurity lengths in this system can be seen as a random impurity with a non-integer average size varying between 1 and 2 depending on the concentration of the monomers in the impurities. We found with the help of the Lyapunov exponent, a range of host lattice potentials for which a crossover between localized and delocalized states exists. This crossover is obtained for different averaged non-integer n-mer sizes and tends to a phase transition when the averaged size goes to an integer value (only dimers). These results can also be extended to higher non-integer n-mer systems. [References: 15]