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1.
The exact static configuration of the soliton in polyacetylene is determined through the self-consistent iterations and the localized modes around the soliton are numerically caiculated. They are compared with the results that the static configuration of the soliton is assumed to be the kink u0tanh(n/L). The comparison shows that the self-consistent configuration improves the Goldstone mode by getting the positive-definite vibrational matrix, whereas the other localized modes change their frequencies only less than 0.03%. It confirms that the five localized modes around the soliton do exist in polyacetylene. 相似文献
2.
We demonstrate that the ENDOR results on polyacetylene are consistent with the soliton model, and that ENDOR data measure the size of the chain segment over which a soliton diffuses. The existence of two discrete sites is a confirmation of the qualitative feature of the soliton gap state wave-function which has amplitude only on alternate sites. The observation of negative spin density (rather than zero) on the second kind of site requires that the model be expanded to include the electron-electron Coulomb interaction which leads to the observed negative exchange polarization. 相似文献
3.
An experimental study of NMR spin-lattice relaxation of 13C in enriched, iodine doped, polyacetylene is presented together with a theoretical analysis of the results based on the existence of solitons in this system. The good agreement with this model and the numerical values obtained here and those measured by different experimental techniques support firmly the applicability of the soliton picture to I2 doped polyacetylene. 相似文献
4.
As a new subject, soliton theory is shown to be an effective tool for describing and explaining nonlinear phenomena in nonlinear optics, super conductivity, plasma physics, magnetic fluid, etc. Thus, the study of soliton equations has always been one of the most prominent events in the field of nonlinear science during the past few years. Moreover, it is important to seek the lattice soliton equation and study its properties. In this study, firstly, we derive a discrete integrable system by using the Tu model. Then, some properties of the obtained equation hierarchies are discussed. 相似文献
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6.
Muramatsu M Nagatani T 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(1):180-187
Soliton density wave is investigated numerically and analytically in the optimal velocity model (a car-following model) of a one-dimensional traffic flow with open boundaries. Soliton density wave is distinguished from the kink density wave. It is shown that the soliton density wave appears only at the threshold of occurrence of traffic jams. The Korteweg-de Vries (KdV) equation is derived from the optimal velocity model by the use of the nonlinear analysis. It is found that the traffic soliton appears only near the neutral stability line. The soliton solution is analytically obtained from the perturbed KdV equation. It is shown that the soliton solution obtained from the nonlinear analysis is consistent with that of the numerical simulation. 相似文献
7.
《Solid State Communications》1987,64(6):947-950
Vibrational frequencies of finite polyacetylene with a charged soliton are calculated using the molecular orbital method. It is found that the frequency of the translational mode has a remarkable length effect and is inversely proportional to the square of chain length. The dependence is explained by regarding the soliton as a quantum particle in a one dimensional box. 相似文献
8.
Dynamical formation processes of self-localized excitations
induced by charge injection or photoexcitations in a polyacene
chain are investigated by a nonadiabatic dynamic method. The
polyacene chain is treated as two alternatively coupled
polyacetylene chains. The initial lattice configuration is taken
as the pristine polyacene chain. It contains an interchain-coupled
neutral soliton as a consequence of odd-number sites in each of
the two chains. The nonadiabatic dynamical processes are carefully
investigated in the following physical cases: (1) electron
injection; (2) electron transition from the highest occupied
molecular orbital (HOMO) to the lowest unoccupied molecular
orbital (LUMO); (3) electron transition from HOMO to the localized
soliton level, and (4) electron-hole pair excited at the continuum
absorbtion edge for light polarized parallel to the chain. It is
interestingly found that the centers of the electron and the hole
excited by light polarized parallel to the chain are separated.
Therefore, the photogenerated charge carriers should be favorable
in polyacene, which is remarkably different from those found in a
single polyacetylene chain. 相似文献
9.
《Physics letters. A》1999,259(5):366-370
The staggered soliton mode, which was first discovered in polyacetylene, was observed by Lou et al. in a one-dimensional nonlinear pendulum-lattice. Some recurrence phenomena of the amplitude of the staggered mode in a macro-lattice system are investigated. The experimental result shows that the amplitude of the envelope soliton changes periodically or quasiperiodically under suitable excited parameters. In addition, a period doubling bifurcation is also observed. 相似文献
10.
L. A. Nesterov Al. S. Kiselev An. S. Kiselev N. N. Rosanov 《Optics and Spectroscopy》2009,106(4):570-588
A quantum Langevin equation is derived that makes it possible to study the radiation field in a large-aperture nonlinear interferometer excited by external classical radiation. This equation is linearized in the vicinity of the solution for a stationary soliton. A mathematical formalism for obtaining a spectral representation of the solution to the linearized problem is constructed. It is shown that, in general, the excitation spectrum of a soliton consists of three branches, two of which belong to a continuous spectrum, while the third branch is discrete. The spectral representation obtained makes it possible to rigorously define the operator of soliton coordinate fluctuations, since, as is shown in the study, the traditional definition of this operator leads to a divergence in the vicinity of the solution. A new type of dissipative soliton is found, which is a natural generalization of a stationary soliton and takes into account its motion. A relation is found between this soliton and the contribution to the solution for field fluctuations from the discrete spectrum expansion. The mean squares of fluctuations of the soliton coordinate and momentum are calculated. A range of parameters is determined where the momentum of the soliton can always be measured with a spread smaller than the standard quantum limit. This possibility is related to the occurrence of states squeezed with respect to the soliton momentum. A scheme is proposed for the experimental observation of these states. 相似文献
11.
《Physics letters. A》1999,262(1):83-85
We present a tight-binding approach of the soliton formations and propagations in superlattices. Negative differential conductivity in superlattices leads to the growth of the inevitable spatial fluctuations and formation of the electron accumulation-layer domain. Based on the negative differential conductivity, it is shown that the envelope of the tight-binding-approach wave functions is governed by the nonlinear Schrödinger equation which has soliton solutions, the result of which suggests soliton formations and propagations in the superlattices. 相似文献
12.
《Solid State Ionics》1987,23(4):275-278
A solid-state lithium/iodine battery has been formed by directly contacting metallic lithium with iondine-doped polyacetylene. The procedure is similar to that used for the well-known lithium/iodine-polyvinylpyridine system. The advantage of the system proposed here may be related to the extraordinary electrical properties of polyacetylene which, when doped with iodine, acquires a very high electrical conductivity over a wide range of halogen concentration. 相似文献
13.
14.
J.W. Brill 《Solid State Communications》2004,130(7):437-439
In recent measurements on the charge-density-wave (CDW) conductor blue bronze (K0.3MoO3), the electro-transmittance and electro-reflectance spectra were searched for intragap states that could be associated with solitons created by injection of electrons into the CDW at the current contacts [Eur. Phys. J. B16 (2000), 295; Eur. Phys. J. B35 (2003) 233]. In this work, we adapt the model of soliton absorption in dimerized polyacetylene to the blue bronze results, to obtain the (order of magnitude) estimate that current induced solitons occur on less than ∼10% of the conducting chains. We discuss the implications of these results on models of soliton lifetimes and motion of CDW phase dislocations. 相似文献
15.
RUAN Hang-Yu LI Zhi-Fang 《理论物理通讯》2008,49(6):1547-1552
Starting from the variable separation approach, the algebraic soliton solution and the solution describing the interaction between line soliton and algebraic soliton are obtained by selecting appropriate seed solution for (2+1)-dimensional ANNV equation. The behaviors of interactions are discussed in detail both analytically and graphically. It is shown that there are two kinds of singular interactions between line soliton and algebraic soliton: 1) the resonant interaction where the algebraic soliton propagates together with the line soliton and persists infinitely; 2) the extremely repulsive interaction where the algebraic soliton affects the motion of the line soliton infinitely apart. 相似文献
16.
《Physica D: Nonlinear Phenomena》1995,85(4):468-484
An asymptotic method is developed to describe a long-term evolution of unstable quasi-plane solitary waves in the Kadomtsev-Petviashvili model for two-dimensional wave media with positive dispersion. An approximate equation is derived for the parameters of soliton transversal modulation and a general solution of this equation is found in an explicit form. It is shown that the development of periodic soliton modulation, in an unstable region, leads to saturation and formation of a two-dimensional stationary wave. This process is accompanied by the radiation of a small-amplitude plane soliton. In a stable region, an amplitude of the modulation is permanently decreasing due to radiation of quasi-harmonic wave packets. The multiperiodic regime of plane soliton self-focusing is also investigated. 相似文献
17.
The results of lattice dynamical calculations on pristine and doped trans- polyacetylene are summarized and a reinterpretation of the vibrational spectrum is suggested. The possibility of the existence in the doped system of a centrosymmetrical molecular defect, consistent with the infrared spectrum, alternative to the soliton defect is discussed. 相似文献
18.
The unstable nonlinear Schrodinger (NLS) equation is solved by the inverse scattering transform. Based on the constructed Zakharov-Shabat equation, it is shown that the soliton solution of the unstable NLS equation can be known from the soliton solution of the usual NLS equation by simply exchanging the tariables. The explicit N-soliton solution and the position shifts due to the collision are thus calculated. 相似文献
19.
Z.F. Liang 《Physics letters. A》2009,374(2):110-115
It is shown that the resonant Davey-Stewartson (RDS) system can pass the Painlev test. By truncating the Laurent series to a constant level term, a dependent variable transformation is naturally derived, which leads to the bilinear forms of the RDS system. From the bilinear equations, through making suitable assumptions, some new soliton solutions are obtained. Some representative profiles of the solitary waves are graphically displayed including the two-line soliton solution, “Y” soliton solution, “V” soliton solution, solitoff, etc. The solutions might be useful to describe the nonlinear phenomena in Madelung fluids, capillarity fluids, and so on. 相似文献