Hopping transport of correlated electrons

Abstract

The random walk theory of hopping transport is extended to treat the intrasite electron-electron interaction in the atomic limit of the Hubbard model. For this two-electron problem the Green matrix solution of the linearised master equation is expanded as a renormalised perturbation series. The authors develop a matrix self-consistency equation for the differential conductivity from which they calculate the DC conductivity. Analytical and numerical calculations are presented for a constant density of states and a repulsive correlation energy U. The numerical calculations show that for large values of U a simple pseudo-particle picture can be applied. For smaller values of U considerable deviations become apparent. The approximations used in the two-electron theory are just the same as in their one-electron random walk theory.