Miller-Abrahams formalism

In the Miller-Abrahams formalism, hopping between sites / and j is determined by the product of a prefactor, an electronic wavefunction overlap... 

Majias and Casado (1995) analyzed the dependence of the carrier drift velocity on the degree of energetic disorder by a simulation technique (Casado and Majias, 1994). The simulations are based on jump rates derived from the Miller-Abrahams formalism. At low fields, the velocity always decreases with increasing disorder. At high fields, however, the presence of small amounts of disorder induces nonmonotonic behavior, showing a maximum of the velocity at nonzero disorder. The results were discussed by an argument based on the distribution of hopping rates in the three spatial directions. 

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