1,624 research outputs found
Partial Synchronization on Complex Networks
Network topology plays an important role in governing the collective
dynamics. Partial synchronization (PaS) on regular networks with a few
non-local links is explored. Different PaS patterns out of the symmetry
breaking are observed for different ways of non-local couplings. The criterion
for the emergence of PaS is studied. The emergence of PaS is related to the
loss of degeneration in Lyapunov exponent spectrum. Theoretical and numerical
analysis indicate that non-local coupling may drastically change the dynamical
feature of the network, emphasizing the important topological dependence of
collective dynamics on complex networks.Comment: 4 pages, 4 figure
Array-induced collective transport in the Brownian motion of coupled nonlinear oscillator systems
Brownian motion of an array of harmonically coupled particles subject to a
periodic substrate potential and driven by an external bias is investigated. In
the linear response limit (small bias), the coupling between particles may
enhance the diffusion process, depending on the competition between the
harmonic chain and the substrate potential. An analytical formula of the
diffusion rate for the single-particle case is also obtained. In the nonlinear
response regime, the moving kink may become phase-locked to its radiated phonon
waves, hence the mobility of the chain may decrease as one increases the
external force.Comment: 4 figures, to appear in Phys. Rev.
Microscopic Modeling of the Growth of Order in an Alloy: Nucleated and Continuous Ordering
We study the early-stages of ordering in using a model Hamiltonian
derived from the effective medium theory of cohesion in metals: an approach
providing a microscopic description of interatomic interactions in alloys. Our
simulations show a crossover from a nucleated growth regime to a region where
the ordering does not follow any simple growth laws. This mirrors the
experimental observations in . The kinetics of growth, obtained from
the simulations, is in semi-quantitative agreement with experiments. The
real-space structures observed in our simulations offer some insight into the
nature of early-stage kineticsComment: 13 pages, Revtex, 3 postscript figures in a second file
Orbital magnetization and its effects in spin-chiral ferromagnetic Kagome lattice
Recently, Berry phase in the semiclassical dynamical of Bloch electrons has
been found to make a correction to the phase-space density of states and a
general multi-band formula for finite-temperature orbital magnetization has
been given [Phys. Rev. Lett. \textbf{97}, 026603 (2006)], where the orbital
magnetization consists of two parts, i.e., the conventional part
and the Berry-phase correction part . Using this general
formula, we theoretically investigate the orbital magnetization and its effects
on thermoelectric transport and magnetic susceptibility properties of the
two-dimensional \textit{kagom\'{e}} lattice with spin anisotropies included.
The study in this paper is highly interesting by the occurrence of nonzero
Chern number in the lattice. The spin chirality parameter (see text)
results in profound effects on the orbital magnetization properties. It is
found that the two parts in orbital magnetization opposite each other. In
particular, we show that and yield the paramagnetic and
diamagnetic responses, respectively. It is further shown that the orbital
magnetization displays fully different behavior in the metallic and insulating
regions, which is due to the different roles and play in
these two regions. The anomalous Nernst conductivity is also calculated, which
displays a peak-valley structure as a function of the electron Fermi energy.Comment: 9 pages, 7 figure
A More Accurate Generalized Gradient Approximation for Solids
We present a new nonempirical density functional generalized gradient
approximation (GGA) that gives significant improvements for lattice constants,
crystal structures, and metal surface energies over the most popular
Perdew-Burke-Ernzerhof (PBE) GGA. The new functional is based on a diffuse
radial cutoff for the exchange-hole in real space, and the analytic gradient
expansion of the exchange energy for small gradients. There are no adjustable
parameters, the constraining conditions of PBE are maintained, and the
functional is easily implemented in existing codes.Comment: 5 pages, corrected the errors of the sublimation energy of Ih ic
Quantum spin Hall effect and spin-charge separation in a kagome lattice
A two-dimensional kagome lattice is theoretically investigated within a
simple tight-binding model, which includes the nearest neighbor hopping term
and the intrinsic spin-orbit interaction between the next nearest neighbors. By
using the topological winding properties of the spin-edge states on the
complex-energy Riemann surface, the spin Hall conductance is obtained to be
quantized as () in insulating phases. This result keeps
consistent with the numerical linear-response calculation and the
\textbf{Z} topological invariance analysis. When the sample boundaries
are connected in twist, by which two defects with flux are introduced, we
obtain the spin-charge separated solitons at 1/3 (or 2/3) filling.Comment: 13 NJP pages, 7 figure
Resonant steps and spatiotemporal dynamics in the damped dc-driven Frenkel-Kontorova chain
Kink dynamics of the damped Frenkel-Kontorova (discrete sine-Gordon) chain
driven by a constant external force are investigated. Resonant steplike
transitions of the average velocity occur due to the competitions between the
moving kinks and their radiated phasonlike modes. A mean-field consideration is
introduced to give a precise prediction of the resonant steps. Slip-stick
motion and spatiotemporal dynamics on those resonant steps are discussed. Our
results can be applied to studies of the fluxon dynamics of 1D
Josephson-junction arrays and ladders, dislocations, tribology and other
fields.Comment: 20 Plain Latex pages, 10 Eps figures, to appear in Phys. Rev.
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