Structural and Dynamical Analysis of a Two—Dimensional Dusty Plasma Lattice

A two-dimensional dusty plasma lattice in an rf discharge was observed.The structural and dynamical porperties were analysed by computing pair correlation function,static structure factor.bond-orientational correlation function and mean square displacement.The bond-orientational correlation function was found to fit into the law of ^-0.25,and the mean square displacement experienced “ballistic“,“subdiffusive“and “diffusive“regimes, both of which together with the other parameters indicate that the two-dimensional dusty plasma stayed at a state between liquid and solid.     

Electronic Transmission Properties of Two—Dimensional Quasi—Lattice

In the framework of the tight binding model,the electronic transmission properties of two-dimensional Penrose lattices with free boundary conditions are studied using the generalized eigenfunction method (Phys.Rev.B 60(1999)13 444).The electronic transmission coefficients for Penrose lattices with different sizes and widths are calculated,and the result shows strong energy dependence because of the quasiperiodic structure and quantum coherent effect.Around the Fermi level E=0,there is an energy region with zero transmission amplitudes,which suggests that the studied systems are insulating.The spatial distributions of several typical electronic states with different transmission coefficients are plotted to display the propagation process.     

Hall Conductivity in a Quasi—Two—Dimensional disordered Electron System

By making use of the diagrammatic techniques in perturbation theory,we have investigated the Hall effect in a quasi-two dimensional disordered electron system.In the weakly localized regime,the analytical expression for quantum correction to Hall conductivity has been obtained using the kubo formalism and quasiclassical approximation.The relevant dimensional crossover behavior from three dimensions to two dimensions with decreasing the interlayer hopping energy is discussed.The quantum interference effect is shown to have a vanishing correction to the Hall coefficient.     

Quantum Poincare Section of a Two—Dimensional Hamiltonian in a Coherent State Representation

We study the quantum behaviour of a quasi-integrable Hamiltonian.The unperturbed Hamiltonian displays degeneracies of energy levels,which become avoided crossing under a nonintegrable perturbation.In this two-dimensional system,the quantum Poincare section plot is constructed in the coherent state representation with the restriction that the centres of the wavepackets are confined at thd classical surface of constant energy.It is found that the quantum Poincare section plot obtained in this way provides an evident counterpart of the classical system.     

Spin—Dependent Scattering Effects and Dimensional Crossover in a Quasi—Two—Dimensional Disordered Electron System

Two kinds of spin-dependent scattering effects (magnetic-impurity and spin-orbit scatterings) are investigated theoretically in a quasi-tow-dimensional (quasi-2D) disordered electron system.By making use of the diagrammatic techniques in perturbation theory,we have calculated the dc conductivity and magnetoresistance due to weak-localization effects,the analytical expressions of them are obtained as functions of the interlayer hopping energy and the characteristic times:elastic,inelastic,magnetic and spin-orbit scattering times.The relevant dimensional crossover behavior from 3D to 2D with decreasing the interlayer coupling is discussed,and the condition for the crossover is shown to be dependent on the aforementioned scattering times.At low temperature there exists a spin-dependent-scattering-induced dimensional crossover in this system.     

Density Distribution of Bose Condensed Gas in a Three—Dimensional Optical Lattice

For the Bose-condensed gas in a magnetic trap and three-dimensional optical lattice,the non-unifrom distribution of the atoms in different lattice sited in investigated and a propagatro method is used to study the evolution of the interference pattern after the combined potentials are switched off.The analytical result of the wavefunction at any time t is given and especially the motion of the side peaks is described by a simple analytical expression.     

Diffusive Limit of a Two Dimensional Kinetic System of Partially Quantized Particles

A quantum-classical coupled system which models the diffusive transport of electrons partially confined in semiconductors nanostructures was presented in Ben Abdallah and Méhats (Proc. Edinb. Math. Soc. 49:513–549, 2006). In this model, electrons are assumed to behave like wave in the confinement direction and to have a classical behaviour in a diffusive regime in the transport direction parallel to the electron gas. It was formally derived from a kinetic system for partially quantized particles thanks to a diffusive limit when the mean free path becomes small with respect to the macroscopic length scale. This paper is devoted to the rigorous study of this limit for a transport in one dimension. In the transport direction, the motion of particles is described by a 1D Boltzmann equation. A Boltzmann-Schrödinger-Poisson system is then considered. Existence of renormalized solutions relying on the study of a quasistatic Schrödinger-Poisson system and on an entropy estimate is established. Its diffusive limit is then considered.     

Stability of Dust Acoustic Waves in Weakly Two—Dimensional Dust Plasma with Vortex—Like Ion Distribution

By considering the vortex-like ion distribution,we know that the nonlinear dust acoustic wave can be described by the modified Korteweg-de Vries equation.If there are high-order transverse perturbations in this system,the governing equation for this system is the modified Kadomtsev-Petviashvili equation.We also find that for this system under the transverse perturbation the one-dimensional solitary wave solution is stable.     

Submergence and Control of Dark Soliton in a Dispersion—Managed System with Random Dispersion Map

Random dispersion map is considered in a dispersion-managed dark soliton system,its influence on soliton propagation and interaction is discussed.It is found that the random dispersion map results in large sidebands leads to submergence of dark soliton,and enhances the interaction between solitons.Finally,nonlinear gain is introduced to suppress the influence effectively.     

Molecular Dynamics Simulation of Microstructure Transitions in a Large-Scale Liquid Metal Al System During Rapid Cooling Processes

We perform a molecular dynamics simulation of microstructure transitions in a large-scale system consisting of 400000 atoms of liquid metal Al by the Clare supercomputer.A cluster-type index method is proposed to describe the structures of various short-range-order clusters in the liquid system.It is demonstrated that the icosahedron cluster (12 0 12 0) plays the most important role in the microstructure transition and that some larger clusters (containing more than 130 atoms) are formed in the system during the rapid cooling processes.It is obvious that the larger clusters are formed by means of combining some middle clusters,and that the middle clusters are formed with several smaller clusters.However,the larger clustens are not formed to be the multi-shell configuration as shown in the mass spectrum analysis of the cluster configurations of Al obtained by gaseous deposition,ionic spray methods and so on.This result can be used to explain the essential distinction between the cluster configurations of Al formed in two different ways.     

Negative Resistance in a Two-Dimensional System with Entropic Barrier

A phenomenon of negative resistance is found in two-dimensional bistable and periodic potentials via Langevin simulation, where output quantities for noise and signal driven system, such as the power-spectrum density modulus and the signal power amplification, can become minima at finite temperatures. In such a system, the curvature of the potential along non-transport degree of freedom at the barrier is larger than that at the local minima. The temperature-dependent effective barrier, i.e. entropic barrier, is introduced via integration over the non-transport variables. The system shows the negative resistance because of the competence between the signal and the entropic barrier.     

Dispersion of Bulk Waves in a Graphene–Dielectric–Graphene Structure

Optics and Spectroscopy - We investigate the dispersion properties of the first waveguide modes in a dielectric film that is coated with graphene layers having different chemical potential values....     

Lattice Bhatnagar—Gross—Krook Simulations of Turbulent Natural Convection in a Cavity

A thermal lattice Bhatnagar-Gross-Krook (LBGK) model with a robust boundary scheme is developed for Boussinesq incompressible fluids.In the model the velocity and temperature fields are solved by two independent LBGK equations which are combined into a coupled equation for the whole system.The two-dimensional natural convection flow of air in a differentially heated cavity of an aspect ratio of four is simulated for the Rayleigh number up to 10^10.The numerical results are found to be in good agreement with those of previous studies.     

Use of Dispersion Relations in ππ and KK^- Coupled-Channel System

Systematic and careful studies are made on the properties of the IJ =00 7rTr and KK^- coupled-channel system, using newly derived dispersion relations between the phase shifts and poles and cuts. The effects of nearby branch point singularities to the determination of the fo（980） resonance are estimated and discussed.     

Band Structure of a two—Dimensional Photonic Crystal with a Triangular Lattice of Anisotropic Elliptic Cylinders

The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystal formed by a triangular lattice of anisotropic elliptic cylinders.After optimizing the parameters of the elliptic cylinders,we find a large bandgap (about 0.0449 ωe,ωe=2πc/α) at high frequencies beside a coexisting large absolute gap(about 0.035ωe) at low frequencies.Numerical results show that the optimal design is very stable under any parameter perturbation.     

Nonlinear Waves in Two-Dimensional （2D） Square Lattice Frenkel-Kontorova （FK） System

A 2D square lattice is studied. By using the continuum approximation, we set up the differential equations of motion for an arbitrary particle in the square lattice which subjects to an external periodic substrate potential. The exact solitary waves of the system are found for special cases. We conclude that the adhesive force f and the angle between propagation directions of upper and lower layers can affect these waves.     

Three—Dimensional Propagation of Magnetohydrodynamic Waves in the Solar Chromophere and Corona

We study the three-dimensional magnetohydrodynamic(MHD) wave propagation in the solar atmosphere consisting of the chromosphere and corona.Pressure enhancement and velocity shear are implemented simultaneously at the bootom of the chromophere.The global propagation of the incurred MHD waves,including fast-mode and slow-mode magnetoacoustic waves as well as Alfven wave,can be identified,Wave front positions obtained numerically with respect to specific waves fit well with those calculated with local MHD wave speeds.