RIGOROUS STUDY OF CHARGED CARRIERS IN ELECTRIC-FIELDS WITH ALTERNATING SITE ENERGIES AND INTERSITE INTERACTIONS

The problem of charged carriers moving in a one-dimensional infinite system subject to a uniform electric field is studied by taking into account the presence of alternating site energies and intersite interactions. Exact results for the energy spectrum and the eigenvectors are obtained by using, the perturbation theory. It is shown that the energy spectrum is that of two interspaced Stark ladders. The role of both alternating site energies and intersite interactions is also discussed. It is found that the enhancement of the alternating site energies and intersite interactions will give rise to an increase in the energy gap between two coupled Stark ladders.