Absence of localization in disordered tight binding models with external electric field: transmission properties

A disordered discrete model with external dc electric field is presented. The hopping term between nearest neighbour sites is consistent with the condition that the acceleration is constant and proportional to the external field in absence of disorder. It is argued that the localization length, related to the disordered system, goes to infinity due to this external dc electric field. So, strong localization does not exist. Calculations were carried out in the band centre and one crossover, between transmission and weak localization, was found for the transmitted current.