Eur. Phys. J. B 51, 87-99 (2006)
https://doi.org/10.1140/epjb/e2006-00192-y

Nonlinear excitations and electric transport in dissipative Morse-Toda lattices

¹ Instituto Pluridisciplinar, Universidad Complutense, Paseo Juan XXIII, 1, 28040 Madrid, Spain
² Faculty of Physics, Saratov State University, Astrakhanskaya 83, 410012 Saratov, Russia
³ Institut für Physik, Humboldt-Universität Berlin, Newtonstr. 15, 12489 Berlin, Germany

Corresponding authors: ^a chetverikovAP@info.sgu.ru - ^b ebeling@physik.hu-berlin.de - ^c mvelarde@pluri.ucm.es

Received: 18 October 2005
Revised: 17 January 2006
Published online: 31 May 2006

Abstract

We investigate the onset and maintenance of nonlinear soliton-like excitations in chains of atoms with Morse interactions at rather high densities, where the exponential repulsion dominates. First we discuss the atomic interactions and approximate the Morse potential by an effective Toda potential with adapted density-dependent parameters. Then we study several mechanisms to generate and stabilize the soliton-like excitations: (i) External forcing: we shake the masses periodically, mimicking a piezoelectric-like excitation, and delay subsequent damping by thermal excitation; (ii) heating, quenching and active friction: we heat up the system to a relatively high temperature Gaussian distribution, then quench to a low temperature, and subsequently stabilize by active friction. Finally, we assume that the atoms in the chain are ionized with free electrons able to move along the lattice. We show that the nonlinear soliton-like excitations running on the chain interact with the electrons. They influence their motion in the presence of an external field creating dynamic bound states (“solectrons”, etc.). We show that these bound states can move very fast and create extra current. The soliton-induced contribution to the current is constant, field-independent for a significant range of values when approaching the zero-field value.