Nonlinear ionic excitations, dynamic bound states, and nonlinear currents in a one-dimensional plasma

We study the role of nonlinear effects in a classical one-dimensional model of a conducting electron-ion system. In particular we investigate the excitations of strongly nonlinear deformed phonons (cnoidal waves, solitons) on electric currents. We show that in a nonlinear lattice a new type of dynamic bound states of solitons and electrons ("solectrons") may be formed. In our simulations we use Langevin dynamics with N = 10 ions and periodic boundary conditions. The electron-ion interaction is modelled by screened Coulomb forces with appropriate cut-off at small distance; the ion-ion interaction is approximated by an exponential repulsion. Under the influence of a weak external electrical field, the charged particles and "solectrons" yield a stochastic current in the direction of the field. We study several mechanisms to generate and maintain the "solectrons". Then we show how the system develops driven ionic solitons moving opposite to the field. Since the extra current driven by the solitons is (nearly) independent on the external field we find a strongly nonlinear current field characteristics corresponding for small fields to a highly conducting state. (c) 2005 WILEY-VCH Verlag G.bH & Co. KGaA, Weinheim