Numerical Calculation of Soliton Transport in Trans-polyacetylene under an External Electric Field
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Soliton dynamics is simulated for trans-polyacetylene single-chain systems using the Su-Schrieffer-Heeger (SSH) model with an additional part to include an external electric field. It is shown that the soliton moves along the chain with a constant speed when an external electric field is applied.Keywords:
Polyacetylene
Constant (computer programming)
Chain (unit)
Dissipative soliton
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Dynamics of a fractionally charged soliton in a nearly 1/3-filled one-dimensional electron-lattice system is numerically investigated with recently developed simulation method of accelerating charged solitons by an external electric field. For the Hamiltonian, Su-Schrieffer-Heeger's model is assumed. A soliton with -2e/3 charge is treated; the numbers of lattice sites and electrons are chosen to be 119 and 80, respectively. The time dependences of the soliton velocity and of the different parts of the system energy are analyzed. The soliton dynamics is studied by decomposing the space-dependent Peierls order parameter into phase and amplitude. The saturation of the soliton velocity is not clearly seen as in the case of the polyacetylene, because the soliton velocity oscillates with time presumably due to the excitation of phase mode. The same oscillation makes the velocity-energy correlation obscure, and therefore it is not possible to derive a unique relation between the total energy and the soliton velocity. Oscillatory behavior of various quantities are discussed in connection to the excitations of linear modes.
Dissipative soliton
Lattice (music)
Oscillation (cell signaling)
Hamiltonian (control theory)
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Polyacetylene
Hamiltonian (control theory)
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The interchain charge transfer and interactions of two chains are studied numerically through the dynamics of charged and neutral solitons in the presence of an electric field by using the Su-Schrieffer-Heeger model. The electric field is introduced in terms of a time-dependent vector potential which is included in the Hamiltonian through a Peierls substitution of the phase factor to the transfer integral. The effects of confinement on the soliton motion are determined. In particular, the viability of a single moving soliton to cross an interacting region between two parallel chains is analyzed, and its relationship to soliton velocity and interaction region extent is determined. The interchain charge-transfer probability is considered. The charge-transfer probability in a collision between a charged and a neutral soliton belonging to neighboring chains is determined. It is shown that a pair of solitons, one on each chain, can move freely together in an oscillatory way, without any confinement. The oscillation frequency is estimated and its relationship to experimental data is clarified.
Hamiltonian (control theory)
Oscillation (cell signaling)
Polyacetylene
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Quantum solitons or polarons are supposed to play a crucial role in the electric conductivity of polyacetylene, in the intermediate doping regime. We present an exact fully quantized calculation of the quantum soliton conductivity in polyacetylene and show that it vanishes exactly. This is obtained by applying a general method of soliton quantization, based on order–disorder duality, to a Z(2)-symmetric complex extension of the TLM dimerization effective field theory. We show that, in this theory, polyacetylene solitons are sine-Gordon solitons in the phase of the complex field.
Polyacetylene
Duality (order theory)
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Dynamical process of the formation of a soliton pair from a photogenerated electron-hole pair in polyacetylene is studied numerically by adopting the SSH Hamiltonian. A weak local disorder is introduced in order to trigger the formation. Starting from an initial configuration with an electron at the bottom of the conduction band and a hole at the top of the valence band, separated by the Peierls gap, the time dependent Schr${\rm \ddot{o}}$ndinger equation for the electron wave functions and the equation of motion for the lattice displacements are solved numerically. After several uniform oscillations of the lattice system at the early stage, a large distortion corresponding to a pair of a soliton and an anti-soliton develops from a point which is determined by the location and type of the disorder. In some cases, two solitons run in opposite directions, leaving breather like oscillations behind, and in other cases they form a bound state emitting acoustic lattice vibrational modes.
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Polyacetylene
Hamiltonian (control theory)
Lattice (music)
Electron hole
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The dynamics of polyacetylene chains have been studied using the Su-Schrieffer-Heeger Hamiltonian and within the adiabatic approximation. We investigate the nature of the various nonlinear excitations of the system, as well as their interactions. It is shown that both solitons and breathers are highly stable and regain their shape after undergoing collisions with remarkable accuracy. A detailed analysis of soliton-antisoliton scattering is given, as well as its effect on the electronic properties of the system.
Polyacetylene
Breather
Hamiltonian (control theory)
Adiabatic theorem
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Electric charge
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We consider soliton–soliton interactions in the damped ac-driven nonlinear Schrödinger equation, which is the simplest model of charge-density wave conductor or of a cold plasma driven by an external ac electric field. Analyzing perturbatively the collision of two solitons with zero initial velocity at infinity, we demonstrate that after the collision the solitons separate at a finite velocity, i.e., a two-soliton breather does not exist in this model. We corroborate this analytical prediction by direct numerical simulations. We also demonstrate that soliton–soliton collisions in the model considered are practically always destructive: after collision, the solitons find themselves kicked out from the stable states, phase-locked to the ac drive, and finally they fully decay under the action of dissipation. Using the results obtained, we calculate a contribution of the solitons to the rate of absorption of energy of the ac field, which is the most important experimentally observable characteristic of the above-mentioned ac-driven systems.
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Abstract Dynamical solutios to a one-dimensional coupled electron-phonon model of polyacetylene are explored numerically. The results indicate that interesting objects in polyacetylene such as neutral spincarrying solitons, charged spinles solitons, polarons and breathers can be dynamically generated by single electron and electron pair tunneling, pgotoabsorption, and chain breaking
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Breather
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Soliton dynamics is studied in a discrete magnetic nano-dot chain by means of micromagnetic simulations together with an analytic model equation. A soliton under a dissipative system is driven by an applied field. The field-driven dissipative soliton enhances its mobility nonlinearly, as the characteristic frequency and the intrinsic Gilbert damping decrease. During the propagation, the soliton emits spin waves which act as an extrinsic damping channel. The characteristic frequency, the maximum velocity, and the localization length of the soliton are found to be proportional to the threshold field, the threshold velocity, and the initial mobility, respectively.
Dissipative soliton
Micromagnetics
Chain (unit)
Dynamics
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