共查询到20条相似文献,搜索用时 62 毫秒
1.
T.R. Hovhannisyan A.G. Markossian G.F. Mkrtchian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):17-25
On the base of relativistic generalized eikonal approximation wave function the multiphoton cross-sections of a Dirac particle
bremsstrahlung on an arbitrary electrostatic potential and strong laser radiation field are presented. In the limit of the
Born approximation the ultimate analytical formulas for arbitrary polarization of electromagnetic wave have been obtained
and numerically analyzed.
Received 5 April 2001 / Received in final form 18 March 2002 Published online 28 June 2002 相似文献
2.
N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):255-259
We consider quasi-periodic and periodic (cnoidal) wave solutions of a set of n-component dynamical systems related to Korteweg-de Vries equation. Quasi-periodic wave solutions for these systems are expressed
in terms of Novikov polynomials. Periodic solutions in terms of Hermite polynomials and generalized Hermite polynomials for
dynamical systems related to Korteweg-de Vries equation are found.
Received 15 October 2001 / Received in final form 6 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: nakostov@ie.bas.bg 相似文献
3.
R. Fedele H. Schamel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):313-320
An investigation to deepen the connection between the family of nonlinear Schr?dinger equations and the one of Korteweg-de
Vries equations is carried out within the context of the Madelung's fluid picture. In particular, under suitable hypothesis
for the current velocity, it is proven that the cubic nonlinear Schr?dinger equation, whose solution is a complex wave function,
can be put in correspondence with the standard Korteweg-de Vries equation, is such a way that the soliton solutions of the
latter are the squared modulus of the envelope soliton solution of the former. Under suitable physical hypothesis for the
current velocity, this correspondence allows us to find envelope soliton solutions of the cubic nonlinear Schr?dinger equation,
starting from the soliton solutions of the associated Korteweg-de Vries equation. In particular, in the case of constant current
velocities, the solitary waves have the amplitude independent of the envelope velocity (which coincides with the constant
current velocity). They are bright or dark envelope solitons and have a phase linearly depending both on space and on time coordinates. In the case of an arbitrarily
large stationary-profile perturbation of the current velocity, envelope solitons are grey or dark and they relate the velocity u0 with the amplitude; in fact, they exist for a limited range of velocities and have a phase nonlinearly depending on the combined
variable x-u0 s (s being a time-like variable). This novel method in solving the nonlinear Schr?dinger equation starting from the Korteweg-de
Vries equation give new insights and represents an alternative key of reading of the dark/grey envelope solitons based on the fluid language. Moreover, a comparison between the solutions found in the
present paper and the ones already known in literature is also presented.
Received 20 February 2002 and Received in final form 22 April 2002 Published online 6 June 2002 相似文献
4.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
5.
D.I. Pushkarov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):295-300
In this work we present a full selfconsistent set of nonlinear equations which unifies the nonlinear elasticity theory equations,
the Boltzmannn transport theory and the Maxwell equations for quasiparticles with arbitrary dispersion laws in nonstationarily
deformed crystals with arbitrary (but linear) constitutive relations. Transformations to replace the Galilean ones are obtained,
the quasiparticle mechanics in a Hamiltonian form is deduced, and a Boltzmann-type transport equation (valid in the whole
Brillouin zone) is derived. The theory may be applied to metals, semiconductors, quantum crystals, low-dimensional structures
etc.
Received 20 October 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: dipushk@issp.bas.bg 相似文献
6.
I.M. Mladenov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):327-330
The general shape equation describing the forms of vesicles is a highly nonlinear partial differential equation for which
only a few explicit solutions are known. These solvable cases are briefly reviewed and a new analytical solution which represents
the class of the constant mean curvature surfaces is described. Pearling states of the tubular fluid membranes can be explained
as a continuous deformation preserving membrane mean curvature.
Received 2 February 2002 / Received in final form 4 February 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: mladenov@obzor.bio21.bas.bg 相似文献
7.
M. Johansson A.M. Morgante S. Aubry G. Kopidakis 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):279-283
Modulational instability of travelling plane waves is often considered as the first step in the formation of intrinsically
localized modes (discrete breathers) in anharmonic lattices. Here, we consider an alternative mechanism for breather formation,
originating in oscillatory instabilities of spatially periodic or quasiperiodic nonlinear standing waves (SWs). These SWs
are constructed for Klein-Gordon or Discrete Nonlinear Schr?dinger lattices as exact time periodic and time reversible multibreather
solutions from the limit of uncoupled oscillators, and merge into harmonic SWs in the small-amplitude limit. Approaching the
linear limit, all SWs with nontrivial wave vectors (0 < Q < π) become unstable through oscillatory instabilities, persisting for arbitrarily small amplitudes in infinite lattices.
The dynamics resulting from these instabilities is found to be qualitatively different for wave vectors smaller than or larger
than π/2, respectively. In one regime persisting breathers are found, while in the other regime the system thermalizes.
Received 6 October 2001 / Received in final form 1st March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: mjn@ifm.liu.se 相似文献
8.
K.T. Stoychev M.T. Primatarowa K. Marinov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):301-304
Effects of the exciton and polariton dispersions and the nonlinear exciton and photon interactions on the properties of polariton
solitons in molecular crystals are investigated. Higher-order terms and phase-modulation (chirp) are taken into account. Bright-
and dark-soliton solutions of the resulting modified nonlinear Schr?dinger (NLS) equation are presented. Nonlinearity- and
dispersion-induced critical points on the polariton dispersion curve are obtained, separating regions with different solutions.
Received 2 October 2001 / Received in final form 23 May 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: Stoychev@issp.bas.bg 相似文献
9.
Y. Pavlyukh W. Hübner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):239-246
We present a method for the numerical investigation of the electron dynamics in small metallic clusters in intense laser fields.
We obtain information about collective excitations and relaxation processes in the Na
9
+
and Pt3 clusters analyzing the power spectrum of the dipole moment within a mean-field approach. The power spectrum is computed for
various laser pulse parameters as well as for the limit of an infinitely short laser pulse. Due to the basis set expansion
of the wave function our method is capable to follow the dynamics not only of the whole electron cloud, but of any particular
molecular orbital.
Received 28 March 2002 / Received in final form 31 May 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: pavlyukh@mpi-halle.de 相似文献
10.
P.K. Shukla R. Fedele M. Onorato N.L. Tsintsadze 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):613-618
The nonlinear coupling between light beams and non-resonant ion density perturbations in a plasma is considered, taking into
account the relativistic particle mass increase and the light beam ponderomotive force. A pair of equations comprising a nonlinear
Schr?dinger equation for light beams and a driven (by the light beam pressure) ion-acoustic wave response is derived. It is
shown that the stationary solutions of our nonlinear equations can be represented in the form of a bright and dark/gray soliton
for the one-dimensional problem. We also present numerical results which exhibit that our bright soliton solutions are stable
exclusively for the values of the parameters compatible with our theory.
Received 24 July 2002 Published online 31 October 2002
RID="a"
ID="a"Permanent address: Dipartimento di Scienze Fisiche, Universitá Federico II and INFN, Complesso Universitario di M.S. Angelo, Via Cintia, 80126
Napoli, Italy e-mail: renato.fedele@na.infn.it
RID="b"
ID="b"Permanent address: Dipartimento di Fisica Generale, Universitá di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
RID="c"
ID="c"Permanent address: Institute of Physics, Georgian Academy of Sciences, Tbilisi 380077, Georgia 相似文献
11.
M. Zamboni-Rached E. Recami H.E. Hernández-Figueroa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):217-228
By a generalized bidirectional decomposition method, we obtain new Superluminal localized solutions to the wave equation (for
the electromagnetic case, in particular) which are suitable for arbitrary frequency bands; several of them being endowed with
finite total energy. We construct, among the others, an infinite family of generalizations of the so-called “X-shaped" waves. Results
of this kind may find application in the other fields in which an essential role is played by a wave-equation (like acoustics,
seismology, geophysics, gravitation, elementary particle physics, etc.).
Received 23 June 2002 Published online 24 September 2002
RID="a"
ID="a"Work partially supported by MIUR and INFN (Italy), and by FAPESP (Brazil). This paper did first appear as e-print physics/0109062
[and as preprint INFN/FM-01/02 (I.N.F.N.; Frascati, 2001)].
RID="b"
ID="b"e-mail: recami@mi.infn.it 相似文献
12.
V. Wippel C. Binder L. Windholz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):101-104
In a magneto-optical trap (MOT) we are able to simultaneously trap and cool 7Li and Na. We investigated the loading behavior of the cloud of Li atoms in presence of the overlapped cloud of cold Na atoms,
and, by blocking the weak repumping beam for Na, compared it with the loading curve for Li atoms only. Out of these loading
curves we calculated the collision cross-section of Na on Li to be 10-11 cm
3
/s.
Received 11 January 2002 / Received in final form 5 April 2002 Published online 24 September 2002 相似文献
13.
P. Schlagheck A. Buchleitner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):401-415
We provide a detailed quantum treatment of the spectral characteristics and of the dynamics of nondispersive two-electron
wave packets along the periodically driven, collinear frozen planet configuration of helium. These highly correlated, long-lived
wave packets arise as a quantum manifestation of regular islands in a mixed classical phase space, which are induced by nonlinear
resonances between the external driving and the unperturbed dynamics of the frozen-planet configuration. Particular emphasis
is given to the dependence of the ionization rates of the wave packet states on the driving field parameters and on the quantum
mechanical phase space resolution, preceded by a comparison of 1D and 3D life times of the unperturbed frozen planet. Furthermore,
we study the effect of a superimposed static electric field component, which, on the grounds of classical considerations,
is expected to stabilize the real 3D dynamics against large (and possibly ionizing) deviations from collinearity.
Received 7 November 2002 / Received in final form 2 December 2002 Published online 28 January 2003 相似文献
14.
Slow dynamics of density fluctuations near the colloidal glass transition is discussed from a new viewpoint by numerically
solving a nonlinear stochastic diffusion equation for the density fluctuations recently proposed by one of the present authors
(MT). The effects of spatial heterogeneities on the dynamics of density fluctuations are then investigated in an equilibrium
system. The spatial heterogeneities are generated by the nonlinear density fluctuations, while in a nonequilibrium system
they are described by a nonlinear deterministic equation for the average number density. The dynamics of equilibrium density
fluctuations is thus shown to be quite different from that of nonequilibrium ones, leading to a logarithmic decay followed
by less distinct α- and β-relaxation processes.
Received 9 March 2002 and Received in final form 19 September 2002 相似文献
15.
P. Hillion 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):527-532
A particular transformation of coordinates, associated with superluminal X-pulses, leaves the wave equation invariant and
changes focus wave modes into superluminal focus wave pulses. Rather simple and manageable expressions for TM electromagnetic
waves allow the investigation of these new localized solutions of Maxwell's equations.
Received 11 June 2002 / Received in final form 27 August 2002 Published online 31 December 2002 相似文献
16.
B.S. Kandemir T. Altanhan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):517-526
We investigate the stability condition of large bipolarons confined in a parabolic potential containing certain parameters
and a uniform magnetic field. The variational wave function is constructed as a product form of electronic parts, consisting
of center of mass and internal motion, and a part of coherent phonons generated by Lee-Low-Pines transformation from the vacuum.
An analytical expression for the bipolaron energy is found, from which the ground and excited-state energies are obtained
numerically by minimization procedure. The bipolaron stability region is determined by comparing the bipolaron energy with
those of two separate polarons, which is already calculated within the same approximation. It is shown that the results obtained
for the ground state energy of bipolarons reduce to the existing works in zero magnetic field. In the presence of a magnetic
field, the stability of bipolarons is examined, for three types of low-dimensional system, as function of certain parameters,
such as the magnetic-field, the electron-phonon coupling constant, Coulomb repulsion and the confinement strength. Numerical
solutions for the energy levels of the ground and first excited states are examined as functions of the same parameters.
Received 7 March 2002 and Received in final form 22 April 2002 Published online 25 June 2002 相似文献
17.
D. Hennig 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(3):419-425
We study localization in polymer chains modeled by the nonlinear discrete Schr?dinger equation (DNLS) with next-nearest-neighbor
(n-n-n) interaction extending beyond the usual nearest-neighbor exchange approximation. Modulational instability of plane
carrier waves is discussed and it is shown that localization gets amplified under the influence of an enhanced interaction
radius. Furthermore, we construct exact localized solitonlike solutions of the n-n-n interaction DNLS. To this end the stationary
lattice system is cast into a nonlinear map. The homoclinic orbits of unstable equilibria of this map are attributed to standing
solitonlike solutions of the lattice system. We note that in comparison with the standard next-neighbor interaction DNLS which
bears only one type of static soliton-like states (either staggering or unstaggering) the one with n-n-n interaction radius
can support unstaggering as well as staggering stationary localized states with frequencies lying above respectively below
the linear band. Generally, the stronger the n-n-n interaction on the DNLS lattice the smaller are the maximal amplitudes
of the standing solitonlike solutions and the less rapid are their exponential decays.
Received 4 October 2000 相似文献
18.
V. Baru J. Haidenbauer C. Hanhart J.A. Niskanen 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):437-446
We present a new parameterization of the trinucleon wave function. As a novel feature a separable parameterization for the
complete wave function is given. In this way any calculation that considers two-body currents only is largely simplified.
To demonstrate this we calculate the π3He scattering length in chiral-perturbation theory. We find reasonable agreement with experimental values inferred from data
on level shifts in pionic 3He bound states. The relevance of the π-triton system for an alternative determination of the πN scattering lengths is discussed.
Received: 12 August 2002 / Accepted: 25 November 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: c.hanhart@fz.juelich.de
Communicated by V. Vento 相似文献
19.
Th. Desaive M. Hennenberg G. Lebon 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):641-647
In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below.
The effect of rotation is restricted to the Coriolis force, neglecting thus the centrifugal effects, the porous medium is
described by Brinkman's model. The linear eigenvalue problem is solved by means of a modified Galerkin method. The behavior
of the critical temperature gradient is discussed in terms of various parameters of the system for both stationary and overstable
convections. Finally a weakly nonlinear analysis is provided to derive amplitude equations and to study the onset of Küppers-Lortz
instability.
Received 24 June 2002 / Received in final form 11 September 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: tdesaive@ulg.ac.be 相似文献
20.
T. Kanna M. Lakshmanan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):249-254
Soliton interactions in systems modelled by coupled nonlinear Schr?dinger (CNLS) equations and encountered in phenomena such
as wave propagation in optical fibers and photorefractive media possess unusual features: shape changing intensity redistributions,
amplitude dependent phase shifts and relative separation distances. We demonstrate these properties in the case of integrable
2-CNLS equations. As a simple example, we consider the stationary two-soliton solution which is equivalent to the so-called
partially coherent soliton (PCS) solution discussed much in the recent literature.
Received 1st October 2001 / Received in final form 4 February 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: lakshman@bdu.ernet.in 相似文献