ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Thermal diffusion of envelope solitons on anharmonic atomic chains (2004)
    Springer
    The European physical journal 42 (2004), S. 103-112 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study the motion of envelope solitons on anharmonic atomic chains in the presence of dissipation and thermal fluctuations. We consider the continuum limit of the discrete system and apply an adiabatic perturbation theory which yields a system of stochastic integro-differential equations for the collective variables of the ansatz for the perturbed envelope soliton. We derive the Fokker-Planck equation of this system and search for a statistically equivalent system of Langevin equations, which shares the same Fokker-Planck equation. We undertake an analytical analysis of the Langevin system and derive an expression for the variance of the soliton position Var[x s ] which predicts a stronger than linear time dependence of Var[x s ] (superdiffusion). We compare these results with simulations for the discrete system and find they agree well. We refer to recent studies where the diffusion of pulse solitons were found to exhibit a superdiffusive behaviour on longer time scales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2004-00361-0
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Diffusion of solitons in anisotropic Heisenberg models (2004)
    Springer
    The European physical journal 42 (2004), S. 381-390 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We are interested in the thermal diffusion of a solitary wave in the anisotropic Heisenberg spin chain (HSC) with nearest-neighbor exchange interactions. The shape of the solitary wave is approximated by soliton solutions of the continuum HSC with on-site anisotropy, restricting ourselves to large width excitations. Temperature is simulated by white noise coupled to the system. The noise affects the shape and position of the solitary wave and produces magnons. Using implicit collective variables we describe the former effects and neglect magnons (i.e. we use the so-called adiabatic approximation). We derive stochastic equations of motion for the collective variables which we treat both analytically and numerically. Predictions for the mean values and the variances of the variables obtained from these equations are compared with the corresponding results from spin dynamics simulations. For the soliton position we find reasonable agreement between spin dynamics and the results of the collective variable treatment, whereas we observe deviations for the other collective variables. The stochastic dynamics of the position shows both a standard Brownian and a super-diffusive component. These results are analogous to results for the isotropic case, previously studied by some of the authors. In the present article we discuss in particular how the anisotropy enters the stochastic equations of motion and the quantitative changes it causes to the diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2004-00394-3
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Theory of angular momentum waves in solid ortho-hydrogen (1968)
    Springer
    The European physical journal 213 (1968), S. 33-45 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Theory of angular momentum waves in pure ortho-hydrogen is presented in the Bloch spin wave approximation. Since there is a large energy gap between the ground state and the excitation this approximation can be justified. Quadrupole-quadrupole interaction of nearest neighbours is used. We have derived some dispersion curves and the spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01380025
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Incoherent neutron scattering by the phonon-libron system in solid ortho-hydrogen (1974)
    Springer
    The European physical journal 267 (1974), S. 31-39 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The incoherent scattering cross section of slow neutrons by ortho hydrogen atT=0 K has been calculated for the case where only one excitation (phonon, libron resp. a mixed mode quantum) is created. The results are compared with the experiment of Stein, Stiller and Stockmeyer and prove that only the coupling of phonons and librons can produce the measured cross section.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01680359
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The three-dimensional transfer-integral method and its test by a harmonic crystal (1978)
    Springer
    The European physical journal 30 (1978), S. 415-421 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ground stateΨ of a simple-cubic crystal is assumed to be a product of single-particle functions and nearest-neighbor (NN) correlation functions. In this so called NNCA (NN-Correlation Approximation) the transfer-integral (TI) method allows an exact integration ofΨ 2 over the coordinates in all cubic planes but one, leading to the probability-densityP for this plane. If only NN-correlations are retained inP (2nd NNCA) the TI-method leads to the probability-density for a row. Finally, after a 3rd NNCA, the 1- and 2-particle probability densities are obtained, which are used to calculate the expectation valueE = 〈Ψ|H|Ψ〉 of a Hamiltonian with arbitrary 2-body interaction.—For harmonic NN-interactions the 2nd and 3rd NNCA become exact, andE differs only by 1% from the exact result. The inclusion of small next-NN-interactions still improves this result, though the 2nd and 3rd NNCA are no longer exact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01321094
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Soliton ratchets out of point-like inhomogeneities (2003)
    Springer
    The European physical journal 37 (2003), S. 79-83 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We introduce and study a novel design for a ratchet potential for soliton excitations. The potential is implemented by means of an array of point-like (delta) inhomogeneities in an otherwise homogeneous potential. We use collective coordinates which predict that the effective potential acting on the soliton is periodic but asymmetric and gives rise to the ratchet effect. Numerical simulations fully confirm this prediction; quantitative agreement is reached by an improved version of the theory. Although we specifically show that it is most interesting for building Josephson junction ratchets capable to rectify time-symmetric ac forces, the proposed mechanism is very general and can appear in many contexts, including biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2004-00031-3
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Correlations and effective potential in the ground state of a one-dimensional model for solid helium and deuterium (1976)
    Springer
    Journal of low temperature physics 22 (1976), S. 653-663 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ground-state energyE can be calculated exactly by the transfer-integral method if the total wave function is assumed to be a product of single-particle functions φ and nearest-neighbor correlation functionsf. The variation ofE with respect tof for fixed φ leads to a Schrödinger equation for the relative motion of two particles which is coupled to the transfer integral equation by an effective potential Vξ. For the case of a Gaussian φ the optimalf, the one- and two-particle probability amplitudes, and other quantities are computed by iteration of the Schrödinger equation with the transfer integral equation until self-consistency is achieved. The minimum ofE as a function of the Gaussian width is obtained for different values of the lattice parameter. The shape of Vξ andf is discussed. The self-consistentf describes both short- and long-range correlations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659066
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Random phase approximation of angular momentum waves in solid Ortho-hydrogen (1969)
    Springer
    The European physical journal 220 (1969), S. 1-5 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A short derivation of the Random Phase Approximation of angular momentum waves in solid Ortho-H2 is presented. Methods and results of papers on the same topic are compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01394406
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Excitation spectrum of the Toda lattice for finite temperatures (1988)
    Springer
    The European physical journal 70 (1988), S. 435-447 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract For the Toda lattice, the integral equations of Yang and Yang are derived for the classical limit and their analytical solutions are given. The introduction of renormalized energies eventually leads to a finite temperature excitation spectrum of classical solitons and semiclassical phonons. The excitation energies are tested by a comparison of the group velocities for vanishing momentum with the sound velocity which can be calculated directly from the thermodynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01312117
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Toda solitons as Fermi-quasiparticles (1987)
    Springer
    The European physical journal 69 (1987), S. 121-127 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Bethe ansatz leads to Yang-Yang integral equations. The particle-hole structure of the zero-temperature excitations is generalized to finite temperatures, which leads to the definition of soliton- and phonon-quasiparticles. The solitons approximately follow the Fermi-Dirac statistics and have a chemical potential with an unusual temperature dependence, because the number of solitons is not constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01560620
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...