International Journal of Modern Physics B

In this work we investigate the fast anomalous diffusion of hydrogen molecules in water using Car–Parrinello molecular dynamics simulations. We employ Voronoi polyhedra analysis to distinguish between void diffusion and void hopping. Our results indicate that a combination of both mechanism is sufficient to explain anomalous diffusion. Furthermore, we investigate the geometrical and electronical structure of the first solvation shell.

The theory of Green's functions (GF) for thin films was formulated, where site indices were different also along the direction of broken symmetry. This approach results in the layer dependence of correlation functions in films, which did not appear in the previous investigations of thin films. The magnetizations of three layer thin ferromagnetic (FM) and four layer thin ferroelectric (FE) films were investigated using the GFs found in this way. It was shown that the transition temperature varies from layer to layer, which is the obvious consequence of the generalization of the formalism of the GF calculation for films.

The analysis of the behavior of elastic material subject to strong short pulse impact has shown that only one-dimensional structures support the impact without destruction. Compact two- and three-dimensional structures are destroyed during the impact along circular lines and spherical surfaces. For that reason, web-like shields are proposed for the protection of man and equipment. Polymer materials are most suitable for the production of web-like shields since they are made of fibers and highly stress resistant. Theoretical results are experimentally tested and the good agreement with theory was found.

In this paper, the concepts of "jammed status" and "jam headway" [X. B. Li, R. Jiang and Q. S. Wu, Phys. Rev.E68, 016117 (2003)] are introduced into the Modified Comfortable Driving (MCD) model [R. Jiang and Q. S. Wu, J. Phys.A36, 381 (2003)] to simulate the congested traffic flow including synchronized flow and wide moving jams. Using computer simulation, the fundamental diagram, the space–time plots, the time series of the density in the jams, the 1-min average data in the flow-density plane, the traffic patterns induced by red light are investigated. It is shown that the new model can describe both the synchronized flow and the sparse wide jams quite well.

There is weak bulk but strong surface coupling between electrons and phonons for many polar crystals. We investigate in this paper the effect of a magnetic field and temperature on the electron in polar crystals which is weakly coupled to the bulk longitudinal optical (LO) phonons while strongly coupled to the surface optical (SO) ones. The magnetic field and temperature dependences of the vibration frequency, the self-trapping energy, the induced potential and the effective interaction potential of the surface magnetopolaron were investigated by using a linear combination operator and variational method. The numerical calculation, taking AgCl crystal as an example, are performed.

We study the dynamics of a single fermionic system interacting non-resonantly with a single mode of a bosonic oscillator coupled to a reservoir. It is shown that the damping rates for both systems are modified when the action of their environments are frequency-dependent. The interest of such demand is discussed.

We show that electromagnetically-induced isotropic dipole–dipole interactions in a spin-polarized non-degenerate fermionic gas can cause an extremely exothermic phase transition, analogous to the isothermal collapse in gravitationally interacting star clusters. This collapse may result in fragmentation of the gas into a hot "halo" and a highly degenerate "core". Possible realization is envisaged in microwave-illuminated fermionic molecular gases at microkelvin temperatures.

We show by means of the theory of order parameter phase fluctuations that the temperature of the "closing" (or "opening") of the gap (and pseudogap) in the electron spectra of superconductors with anisotropic order parameter actually takes place within a finite temperature range. Every Fourier-component of the order parameter has its own critical temperature.

Multi-species reaction-diffusion systems, with more-than-two-site interaction on a one-dimensional lattice are considered. Necessary and sufficient constraints on the interaction rates are obtained, that guarantee the closure of the time evolution equation for , the expectation value of the product of certain linear combination of the number operators on n consecutive sites at time t.

In this paper, an argon-like canonical system is studied. We introduce five hypothesis to deal with the total potential of the system. Then the balanced liquid–gas coexistence phenomenon is analyzed. Good equations of state and phase diagram are given.

The coherent transport through a quantum-dot (QD) coupled with single-wall carbon nanotubes (SWCNs) is investigated by employing the nonequilibrium Green's function (NGF) technique. An external microwave field is applied to the central QD to induce side-bands in addition to the energy levels of the QD. The SWCNs act as quantum wires which open quantum channels for electron to transport through. The novel behaviors are obtained in differential conductance and tunneling current, which are strongly associated with the density of states (DOS) of leads. The hybrid system with a QD coupled to normal metal and SWCN is also investigated as a comparison. The armchair SWCN lead provides rich tunneling channels compared with that of a metal lead. The I–V characteristics is calculated to exhibit stair-like structures which correspond to the resonant peaks of differential conductance versus source–drain bias. The current resonance with the gate voltage is shown to exhibit the photon-assisted tunneling.

By using different times of sputtering and different value of partial pressure of oxygen in sputtering gas, Bi_2.1Sr_1.9CuO_y thin films (Bi:2201) were deposited onto heated single crystal (100) MgO substrates. The temperature dependence of the in-plane resistivity measured on epitaxial c-axis thin films is strongly influenced by the thin films synthesis conditions. Electrical resistivity changes strongly from optimal doping superconducting state to underdoped insulator state with decreasing partial pressure in sputtering gas. The increase of electrical resistance near superconducting transition were analyzed by using some theoretical models.