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Nonlinear excitations and electric transport in dissipative Morse-Toda lattices
Authors:A P Chetverikov  W Ebeling  M G Velarde
Institution: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-Universit?t Berlin, Newtonstr. 15, 12489, Berlin, Germany
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.
Keywords:05  70  Fh Phase transitions: general studies  05  40  Jc Brownian motion  05  70  Ln  Nonequilibrium and irreversible thermodynamics
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