70 research outputs found
Absence of Chaos in Bohmian Dynamics
The Bohm motion for a particle moving on the line in a quantum state that is
a superposition of n+1 energy eigenstates is quasiperiodic with n frequencies.Comment: 1 pag
Dynamics of the Potts model on a fractal lattice
The dynamics of the q-state Potts model on a fractal lattice is studied using Monte Carlo simulations. The Glauber dynamics is used leading to an effective temperature-dependent critical exponent of the form z = AK + B implying the breakdown of conventional dynamic scaling. The value of A is shown to be independent of q, within the error bars
Dynamical properties of an harmonic oscillator impacting a vibrating wall
The dynamics of a spring-mass system under repeated impact with a vibrating wall is investigated using the static wall approximation. The evolution of the harmonic oscillator is described by two coupled difference equations. These equations are solved numerically, and in some cases exact analytical expressions have also been found. For a periodically vibrating wall, Fermi acceleration is only found at resonance. There, the average rebounding velocity increases linearly with the number of collisions. Near resonance, the average rebounding velocity grows initially with the number of collisions and eventually reaches a plateau. In the vicinity of resonance, the motion of the oscillator exhibits scaling properties over a range of frequency ratios. The presence of dissipation at resonance destroys the Fermi-acceleration process and induces scaling behavior similar to that at near resonance. For a moving wall with a random amplitude at collisions, Fermi acceleration is observed independently of the ratio between the wall and oscillator frequencies. In this case the average rebounding velocity grows with the square root of the number of collisions with the wall. Also, in this latter case, dissipation suppresses the Fermi-acceleration mechanism and induces a scaling behavior with the same universality class as that of the dissipative bouncing ball model with random external perturbations
Quantum fidelity approach to the ground state properties of the 1D ANNNI model in a transverse field
In this work we analyze the ground-state properties of the
one-dimensional ANNNI model in a transverse field using the quantum fidelity
approach. We numerically determined the fidelity susceptibility as a function
of the transverse field and the strength of the next-nearest-neighbor
interaction , for systems of up to 24 spins. We also examine the
ground-state vector with respect to the spatial ordering of the spins. The
ground-state phase diagram shows ferromagnetic, paramagnetic, floating,
phases, and we predict an infinite number of modulated phases in
the thermodynamic limit (). The transition lines
separating the modulated phases seem to be of second-order, whereas the line
between the floating and the phases is possibly of first-order.Comment: 10 pages, 20 figure
Corrections to scaling for diffusion in disordered media
We study the diffusion of a particle in a d-dimensional lattice where disorder arises from a random distribution of waiting times associated with each site of the lattice. Using scaling arguments we derive, in addition to the leading asymptotic behaviour, the correction-to-scaling terms for the mean square displacement. We also perform detailed Monte Carlo simulations for one, two and three dimensions which give results in substantial agreement with the scaling argument predictions
Comment on Long-Time Dynamics via Direct Summation of Infinite Continued Fractions
A Comment on the Letter by Z.-X. Cai et al., Phys. Rev. Lett. 68, 1637 (1992)
Reply to ‘Comment on “Breakdown of Hydrodynamics in the Classical 1-D Heisenberg Model,\u27” by Bohm et al
Breakdown of Hydrodynamics in the Classical ID Heisenberg Model
Extensive spin‐dynamics simulations have been performed to study the dynamical behavior of the classical Heisenberg chain at infinite temperatures and long wavelengths. We find that the energy and spin show distinctly different dynamics in the isotropic system. The energy correlation function follows the classical diffusion theory prediction, namely, it decays exponentially with q 2 t. In contrast, the spin correlation function is found to decay exponentially as q 2.12 t ln t implying a logarithmically divergent diffusion constant and the failure of the usual hydrodynamic assumptions
- …