A field method for integrating the equations of motion for
mechanico--electrical coupling dynamical systems is studied. Two
examples in mechanico--electrical engineering are given to
illustrate this method.

This paper studies a time delay equation for sea--air oscillator
model. The existence and asymptotic estimates of periodic solutions
of corresponding problem are obtained by employing the technique of
upper and lower solution, and by using the continuation theorem of
coincidence degree theory.

The collective synchronization of a system of coupled logistic maps
on random community networks is investigated. It is found that the
synchronizability of the community network is affected by two factors
when the size of the network and the number of connections are fixed.
One is the number of communities denoted by the parameter $m$, and
the other is the ratio $\sigma$ of the connection probability $p$ of
each pair of nodes within each community to the connection
probability $q$ of each pair of nodes among different communities.
Theoretical analysis and numerical results indicate that larger $m$
and smaller $\sigma$ are the key to the enhancement of network
synchronizability. We also testify synchronous properties of the
system by analysing the largest Lyapunov exponents of the system.

For a perturbed mechanical system in phase space, considering
${\tilde{{\rm d}}}/{ {{\rm d}t}}$ in the structure equation and
process of proof including infinitesimal parameter $\varepsilon $
obviously, this paper studies the perturbation to Mei symmetry and
adiabatic invariants. Firstly, the exact invariant induced directly
from the Mei symmetry of the system without perturbation is given.
Secondly, based on the concept of high-order adiabatic invariant,
the determining equations of the perturbation to Mei symmetry are
established, the condition of existence of the Mei adiabatic
invariant led by the perturbation to Mei symmetry is obtained, and
its form is presented. Lastly, an example is given to illustrate the
application of the results.

This paper studies two new types of conserved quantities deduced by
Noether--Mei symmetry of mechanical system in phase space. The
definition and criterion of Noether--Mei symmetry for the system are
given. A coordination function is introduced, and the conditions
under which the Noether--Mei symmetry leads to the two types of
conserved quantities and the forms of the two types of conserved
quantities are obtained. An illustrative example is given. The
coordination function can be selected according to the demand for
finding the gauge function, and the choice of the coordination
function has multiformity, so more conserved quantities deduced from
Noether--Mei symmetry of mechanical system can be obtained.

The perturbation to Lie symmetry and another type of Hojman
adiabatic invariants induced from the perturbation to Lie symmetry
for Birkhoffian systems are studied. The exact invariants of Lie
symmetry for the system without perturbation are given. Based on the
concept of adiabatic invariant, the perturbation to Lie symmetry is
discussed and another new type of Hojman adiabatic invariants that
have the different form from that in [{\em Acta Phys. Sin.} {\bf 55}
3833] for the perturbed system are obtained.

We propose the methods of generating multipartite entanglement by
considering the interaction of a system of $N$ two-level atoms in $M$
cavities of high quality factor with a strong classical driving
field. It is shown that, with the cavity detuning, the applied
driving field detuning and vacuum Rabi coupling, we can produce an
entangled coherent state in two single-mode cavities and generate the
entangled coherent cluster states in two bimodal vacuum cavities.
Tuning these parameters also allows us to acquire the
anti-Jaynes--Cummings (AJC) interaction, with which we can generate
the maximally two-photon entangled states, and the two-atom and the
two-photon entangled cluster states.

In this paper, a scheme for generating various multiatom entangled
graph states via resonant interactions is proposed. We investigate
the generation of various four-atom graph states first in the ideal
case and then in the case in which the cavity decay and atomic
spontaneous emission are taken into consideration in the process of
interaction. More importantly, we improve the possible distortion of
the graph states coming from cavity decay and atomic spontaneous
emission by performing appropriate unitary transforms on atoms. The
generation of multiatom entangled graph states is very important for
constructing quantum one-way computer in a fault-tolerant manner.
The resonant interaction time is very short, which is important in
the sense of decoherence. Our scheme is easy and feasible within the
reach of current experimental technology.

This paper investigates the resonant frequencies of the massless
scalar field in the near extremal Kerr-like black-brane spacetime.
It is shown that the different angular quantum number will present
different resonant frequencies. It is also shown that the real part
of the resonant frequencies increases as the compact dimensions
parameter $\mu_i$ increases, but the magnitude of the imaginary part
decreases as $\mu_i$ increases.

In this paper, we introduce a noise which is composed of
multiplication of two dichotomous noises, and derive the probability
density and the statistical properties of this noise. The obtained
results can help study the resonant activation phenomenon, the
phenomenon of stochastic resonance, the transport of particles, and
the nonequilibrium (phase) transition for the systems driven by this
noise.

In the real world, the inputs of many complicated systems are
time-varying functions or processes. In order to predict the outputs
of these systems with high speed and accuracy, this paper proposes a
time series prediction model based on the wavelet process neural
network, and develops the corresponding learning algorithm based on
the expansion of the orthogonal basis functions. The effectiveness
of the proposed time series prediction model and its learning
algorithm is proved by the Mackey--Glass time series prediction, and
the comparative prediction results indicate that the proposed time
series prediction model based on the wavelet process neural network
seems to perform well and appears suitable for using as a good tool
to predict the highly complex nonlinear time series.

This paper detects and characterizes the diverse roles played by
bounded noise in chaotic phase synchronization (CPS) of weakly
coupled nonlinear stochastic systems. Analysis of a paradigmatic
model of two bidirectional coupled three-level food chains is
carried out by various statistical measures such as Shannon entropy
and mutual information. The results indicate that inside the
synchronous regime, CPS is considerably reduced under the influence
of bounded noise; near the onset of phase synchronization, temporal
phase locking is diversely changed with the increase of noise, i.e.,
either weak or strong noise also degrades the degree of CPS, while
intermediate noise enhances CPS remarkably, and an optimal noise
intensity is detected that maximizes the enhancement.

This paper studies dynamics of a modulation-doped GaAs/AlGaAs
heterostructure under transverse magnetic fields and microwave
radiations. It finds that negative differential conductivity, due to
the real-space electron transfer and delayed dielectric relaxation of
the interface potential barrier, can lead to complex behaviours when
a relatively small magnetic field is applied. Quasiperiodicity,
frequency-locking and the routes from period-doubling to chaos are
found. Under a large magnetic field, however, two time-independent
homogeneous steady states exist; and the longitudinal resistance of
the system shows an interesting oscillation with period tuned by the
ratio of microwave radiation frequency $\omega$ to the cyclotron
frequency $\omega_{\rm c}$ and local minima at $\omega/\omega_{\rm
c}={\rm integer}+1/4$.

This paper is a further work of the authors' paper published
previously (Liao T H and Gao Q 2005 {\it Chin. Phys. Lett.} {\bf 22}
2316). The amplitudes of fractional Fourier transform of Cantor sets
are analysed from the viewpoint of multifractal by wavelet transform
maxima method (WTMM). An integral operation is carried out before the
application of WTMM, such that the function obtained can be
considered as the perturbed devil staircase. Also, wavelets with
large number of vanishing moments are used, which makes the complete
singularity spectrum more accessible. The validity of multifractal
formalism is guaranteed by restricting parameter $q$ to a proper
range, so that the phenomenon of multifractal phase transition can be
explained reasonably. Particularly, the method of determining the
range of parameter $q$ in the above paper is developed to be more
operational and rigorous.

Using the different level of methods B3P86, BLYP、B3PW91, HF,
QCISD、CASSCF (4,4) and MP2 with the various basis functions
6-311G**, D95, cc--pVTZ and DGDZVP, the calculations of this paper
confirm that the ground state is $\tilde {X}{ }^3B_1 $ with $C_{2v} $
group for CH$_{2}$. Furthermore, the three kinds of theoretical
methods, i.e. B3P86、CCSD(T, MP4) and G2 with the same basis set
cc-pVTZ only are used to recalculate the zero-point energy revision
which are modified by scaling factor 0.989 for the high level based
on the virial theorem, and also with the correction for basis set
superposition error. These results are also contrary to $\tilde {X}{
}^3\Si _{\rm g} ^ - $ for the ground state of CH$_{2}$ in reference.
Based on the atomic and molecular reaction statics, this paper proves
that the decomposition type (1) i.e. CH$_{4}\to $CH$_{2}$+H$_{2}$, is
forbidden and the decomposition type (2) i.e. CH$_{4} \to $CH$_{3}$+H
is allowed for CH$_{4}$. This is similar to the decomposition of
SiH$_{4}$.

Based on relativistic multichannel theory, this paper calculates the
energy levels of autoionization Rydberg series 4s^{2}
nf(n=4-23)J^{π} =(7/2)^{0} of scandium at different levels of
approximation within the framework of multichannel quantum defect
theory. The present results show that the dipole polarizations play
an important role. Considering the dynamical dipole polarization
effects, this paper finds that the difference between calculated and
experimental quantum defects for the 4s^{2}nf(n=4-23)J^{π}
=(7/2)^{0} series is generally about 0.01--0.03. Furthermore, the
reason that 4s^{2}16f is obscured in experimental spectra is
suggested to be the interaction with the neighbouring resonance state
converged to 3d^{2}(^{1}G_{4} ) of Sc^{+}.

In a recent XUV photoabsorption spectrum of Cs III ions by Cummings
and O'Sullivan [2001 {\em J. Phys.} B {\bf 34} 199], rather large
linewidths were found for the ${\rm 4d}^{\,9} {\rm 5s}^2 {\rm 5p}^6
\,- \,{\rm 4d}^{\,10} {\rm 5s}^2 {\rm 5p}^5$ transition which are
quite in disagreement with corresponding quasi-relativistic
multiconfiguration Hartree--Fock (MCHF) calculation. In the present
work, a detailed multiconfiguration Dirac-Fock study has been carried
out to explore this discrepancy. Owing to the detailed consideration
of electron correlation effects, some 'forbidden' Auger decay
channels, such as ${\rm 4d}^{\,10} {\rm 5s}^2 {\rm 5p}^3 {\rm 5d} $
and ${\rm 4d}^{\,10} {\rm 5s}^0 {\rm 5p}^6 $, would become `open'. As
a result, remarkable improvement of the linewidths has been obtained
in our calculation. Furthermore, the theoretical Auger spectrum of
the ${\rm 4d}^{\,9} {\rm 5s}^2 {\rm 5p}^6$ core-excited states of Cs
III ions is given in the present work.

This paper reports that the splitting of potential energy curves for
the low-lying or low excited states for hydride molecules (cations)
(MgH, AlH^{+}, SiH, PH^{+}, SH,ClH^{+} of the third
period under Spin-Orbit Coupling has been calculated by using the
Spin-Orbit Multi-Configuration Quasi-Degenerate Perturbation Theory
(SO-MCQDPT) method. Then, spectroscopic constants of the split states
have been derived from the Murrell--Sorbie function. The calculated
dissociation energies for the spectrum branch terms have been given,
respectively. The spectroscopic constants and dissociation energies
for the spectrum branch terms are given for the first time in this
paper.

This paper studies full vibrational spectra {\{}$E_\upsilon ${\}} and
molecular dissociation energies $D_\e$ by using conventional
least-squares (LS) fitting and an algebraic method (AM) proposed
recently for 10 diatomic electronic states of ${ }^7$Li$_2 $, Na$_2$,
NaK and NaLi molecules based on some known experimental vibrational
energies in a subset [$E_\upsilon ^{\exp t} $] respectively. Studies
show that: (1) although both the full AM spectrum {\{}$E_\upsilon
^{\rm AM} ${\}} and the LS spectrum {\{}$E_\upsilon ^{\rm LS} ${\}}
can reproduce the known experimental energies in [$E_\upsilon ^{\exp
t} $], the {\{}$E_\upsilon ^{\rm AM} ${\}} is superior to the
{\{}$E_\upsilon ^{\rm LS} ${\}} in that the high-lying AM vibrational
energies which may not be available experimentally have better or
much better accuracy than those LS counterparts in {\{}$E_\upsilon
^{\rm LS} ${\}}, and so is the AM dissociation energy $D_\e^{\rm AM}
$; (2) the main source of the errors in the data obtained by using
the LS fitting is that the fitting which is just a pure mathematical
process does not use any physical criteria that must be satisfied by
the full vibrational spectrum, while the AM method does. This study
suggests that when fitting or solving a physical equation using a set
of source data, it is important not only to apply a proper
mathematical tool, but also to use correct physical criteria which
measure the physical properties of the data, kick out those data
having bigger errors, and impose conditional convergence on the
numerical process.

Single caesium atoms in a large-magnetic-gradient vapour-cell
magneto-optical trap have been identified. The trapping of individual
atoms is marked by the steps in fluorescence signal corresponding to
the capture or loss of single atoms. The typical magnetic gradient is
about 29\,mT/cm, which evidently reduces the capture rate of
magneto-optical trap.

The morphology and properties of nanostructures are significantly
influenced by the chemical coordination during their growth
procedure. Using small molecule N-vinyl pyrolidone as stabilizer,
this paper introduces a new strategy for synthesis of palladium
nanospheres, which has a novel surface plasmon resonance band in the
visible range. An aggregation growth mode was observed in the growth
process. More specifically, the growth rate increases with
increasing concentration of stabilizer. The absorption in visible
region suggests new optical applications for these Pd nanospheres,
such as photocatalysis, photothermal heating and surface enhanced
Raman scattering.

This paper calculates quantum-mechanically the photoelectron energy
spectra excited by attosecond x-rays in the presence of a few-cycle
laser. A photoelectron laser phase determination method is used for
precise measurements of the pulse natural properties of x-ray
intensity and the instantaneous frequency profiles. As a direct
procedure without any previous pulse profile assumptions and
time-resolved measurements as well as data fitting analysis, this
method can be used to improve the time resolutions of attosecond
timing and measurements with metrological precision. The measurement
range is half of a laser optical cycle.

Collisional quantum interference (CQI) in the intramolecular
rotational energy transfer was observed in experiment by Sha and
co-workers.$^{[1]}$ The interference angle, which measuring the
degree of the coherence, were measured in the experiment of the
static cell. Based on the first Born approximation of time dependent
perturbation theory, taking into accounts the anisotropic
Lennard-Jones interaction potentials, this paper describes the
theoretical model of CQI in intramolecular rotational energy transfer
in an atom--diatom collision system. In the model, the differential
interference angle for the experiment of the molecular beam is
calculated, the changing tendencies of the differential interference
angle with the impact parameter and collision partners are obtained.
This theoretical model is important for understanding or performing
this kind of experiments.

This paper reports that the equilibrium structure of NH_{2} has
been optimized at the QCISD/6-311++G (3df, 3pd) level. The
ground-state NH_{2} has a bent (C_{2v}, $X^{2}B_{1} structure
with an angle of 103.0582^{0}. The geometrical structure is in
good agreement with the other calculational and experimental
results. The harmonic frequencies and the force constants have also
been calculated. Based on the group theory and the principle of
microscopic reversibility, the dissociation limits of
NH_{2}(C_{2v}, X^{2}B_{1} have been derived. The potential
energy surface of NH_{2}(X^{2}B_{1} is reasonable. The contour
lines are constructed, the structure and energy of NH_{2} reappear
on the potential energy surface.

This paper reports that the interaction potential for the X^{3}\Si^{-} state of NH radical is constructed at the CCSD(T)/ cc-PV6Z
level of theory. Using this potential, this paper calculates the
spectroscopic parameters ($D_{\e}$, $R_{\e}$, \textit{$\omega
$}$_{\e}$, \textit{$\omega $}$_{\e}$\textit{$\chi $}$_{\e}$,
\textit{$\alpha $}$_{\e}$ and $B_{\e})$ and their values are of
3.578\,eV, 0.10368\,nm, 3286.833\,cm^{-1}, 78.433\,cm^{-1},
0.6469\,cm^{-1} and 16.6735\,cm^{-1}, respectively, which are
in excellent agreement with the experiments. Then the total of 14
vibrational states has been found when $J$=0 by solving the radial
Schr\"{o}dinger equation of nuclear motion. For each vibrational
state, the vibrational manifolds are reported for the first time. And
last, the total cross sections, s-wave, p-wave and d-wave cross
sections are computed for the elastic collisions between two
ground-state atoms (hydrogen and nitrogen) at low temperatures. It
finds that the total elastic cross sections are dominated by s-wave
scattering when the collision energy is below 10^{-6}a.u. The
pronounced shape resonance is found at energy of 6.1$\times $10^{-6}a.u. Calculations have shown that the shape resonance comes from
the p-wave contributions.

This paper reports that an exact quantum close coupling calculation
is carried out for rotational excitation in Ne--HF collisions on the
available anisotropic potential. Partial cross sections are obtained
separately at the incident energies of 48.35, 75, 120 and 150\,meV.
The reliability of the results is demonstrated by comparison with
previously published theoretical findings. Based on the calculations,
the effect of the potential energy surface on the excitation partial
cross sections is discussed in detail.

Taking into consideration the changes of the geometric shielding
effect in a molecule as the energy of incident electrons varies,
this paper presents an empirical fraction, which depends on the
energy of incident electrons, the target's molecular dimension and
the atomic and electronic numbers in the molecule. Using this
empirical fraction, it proposes a new formulation of the additivity
rule. Employing the new additivity rule, it calculates the total
cross sections of electron scattering by C$_{2}$H$_{4}$,
C$_{6}$H$_{6}$, C$_{6}$H$_{14}$ and C$_{8}$H$_{18}$ over the energy
range from 50 to 5000\,eV. In order to exclude the calculation
deviations caused by solving the radial Schr\"{o}dinger equation of
electron scattering by atoms, here the atomic cross sections are
derived from the experimental total cross section results of simple
molecules (H$_{2}$, O$_{2}$, CO) via the inversion algorithm. The
quantitative total cross sections are compared with those obtained
by experiments and other theories, and good agreement is obtained
over a wide energy range, even at energy of several tens of eV.

Employing first-principles methods, based on the density functional
theory, this paper investigates the ground state geometric and
electronic properties of pure gold clusters, pure yttrium clusters
and gold clusters doped each with one yttrium atom. It is shown that
the average bond lengths in the Au$_{n - 1}$Y($n \le $9) bimetallic
clusters are shorter than those in the corresponding pure gold and
yttrium clusters. The most stable isomers of the yttrium-doped gold
clusters tend to equally delocalize valence s, p and d electrons of
the constituent atoms over the entire structure. The Y atom has
maximum number of neighbouring Au atom, which tends to be
energetically favourable in the lowest-energy equilibrium structures,
because the Au--Y bond is stronger than the Au-Au bond. The
three-dimensional isomers of Au$_{n - 1}$Y structures are found in an
early appearance starting at $n$=5 (Au$_{4}$Y). Calculated vertical
ionization potential and electron affinities as a function of the
cluster size show odd-even oscillatory behaviour, and resemble pure
gold clusters. However, one of the most striking feature of pure
yttrium clusters is the absence of odd-even alternation, in agreement
with mass spectrometric observations. The HOMO--LUMO gap of Au$_{3}$Y
is the biggest in all the doped Au$_{n - 1}$Y($n \le $9) bimetallic
clusters.

This paper computationally investigates the RhSi$_{n}(n=1$--$6)$
clusters by using a density functional approach. Geometry
optimizations of the RhSi$_{n}(n=1$--$6)$ clusters are carried out at
the B3LYP level employing LanL2DZ basis sets. It presents and
discusses the equilibrium geometries of the RhSi$_{n}(n=1$--$6)$
clusters as well as the corresponding averaged binding energies,
fragmentation energies, natural populations, magnetic properties, and
the energy gaps between the highest occupied molecular orbital and
the lowest unoccupied molecular orbital. Theoretical results show
that the most stable RhSi$_{n}(n=1$--$6)$ isomers keep an analogous
framework of the corresponding Si$_{n + 1 }$ clusters, the RhSi$_{3}$
is the most stable cluster in RhSi$_{n}(n=1$--$6)$ isomers.
Furthermore, the charges of the lowest-energy RhSi$_{n}(n=1$--$6)$
clusters transfer mainly from Si atom to Rh atom. Meanwhile, the
magnetic moments of the RhSi$_{n}(n=1$--$6)$ arises from the 4d
orbits of Rh atom. Finally, compared with the Si$_{n+1}$ cluster, the
chemical stability RhSi$_{n}$ clusters are universally improved.

The effect of the laser spot size on the neutron yield of table-top
nuclear fusion from explosions of a femtosecond intense laser pulse
heated deuterium clusters is investigated by using a simplified
model, in which the cluster size distribution and the energy
attenuation of the laser as it propagates through the cluster jet are
taken into account. It has been found that there exists a proper
laser spot size for the maximum fusion neutron yield for a given
laser pulse and a specific deuterium gas cluster jet. The proper spot
size, which is dependent on the laser parameters and the cluster jet
parameters, has been calculated and compared with the available
experimental data. A reasonable agreement between the calculated
results and the published experimental results is found.

This paper describes a micro thermal shear stress sensor with a
cavity underneath, based on vacuum anodic bonding and bulk
micromachined technology. A Ti/Pt alloy strip, 2$\mu $m$\times
$100$\mu $m, is deposited on the top of a thin silicon nitride
diaphragm and functioned as the thermal sensor element. By using
vacuum anodic bonding and bulk-si anisotropic wet etching process
instead of the sacrificial-layer technique, a cavity, functioned as
the adiabatic vacuum chamber, 200$\mu $m$\times $200$\mu $m$^{
}\times $400$\mu $m, is placed between the silicon nitride diaphragm
and glass (Corning 7740). This method totally avoid adhesion problem
which is a major issue of the sacrificial-layer technique.

This paper studies entanglement between two dipole--dipole coupled
atoms interacting with a thermal field via a two-photon process. It
shows that the entanglement is dependent on the mean photon number of
the thermal field and the dipole--dipole interaction. The results
also show that the atom--atom entanglement through the two-photon
process is larger than that through the one-photon process and a
remarkable amount of entanglement between the atoms still remains at
certain times even for a very highly noisy thermal field.

This paper proposes a scheme for the generation of entangled coherent
states for two cavity modes. In the scheme a V-type three-level atom
is sent through a two-mode cavity filled with a coherent field. After
the atom--cavity interaction and detection of the atomic state the
cavity modes may evolve to a superposition of two-mode coherent
states. As the scheme is based on resonant atom--cavity interaction,
the required interaction time is short, which is important in view of
the decoherence. Moreover, additional classical pulses are unnecessary
before and after the atom--cavity interaction.

This paper studies the narrow spectral feature appearing in a
four-level system coupled by two strong coherent fields and probed
by a weak laser field. The linewidth is examined as a function of
the Rabi frequencies of coupling fields, and the result is explained
by using the dressed-state formalism.

Two Nd:YAG lasers operating at 1064\,nm are separately servo-locked
to two vertically mounted ultra-stable cavities. The optical
heterodyne beat between two cavity-stabilized lasers shows that the
linewidth of each laser reaches 2\,Hz and the average frequency
drift reduces to less than 1\,Hz/s.

This paper reports that the pattern formation in homogeneous
solutions of polyisoprene in toluene saturated with C$_{60}$ induced
by a continuous-wave visible laser is observed experimentally. The
transmitted beam patterns change with the increase of the laser
irradiation time. In the initial phase, the patterns with concentric
ring-shaped structure are formed. In the end, the patterns become
speckle-shaped. The incubation time of the transmitted beam widening
is inversely proportional to the laser power density and solution
concentration. The pattern formation results from the
optical-field-induced refractive index changes in the solutions, but
the mechanism of optical-field-induced refractive index changes in
the polymer solutions needs to be further studied.

We systematically investigate the motion of slowly moving
matter--wave gap solitons in a nonlinear potential, produced by the
weak random spatial variation of the atomic scattering length. With
the weak randomness, we construct an effective-particle theory to
study the motion of gap solitons. Based on the effective-particle
theory, the effect of the randomness on gap solitons is obtained, and
the motion of gap solitons is finally solved. Moreover, the analytic
results for the general behaviours of gap soliton motion, such as the
ensemble-average speed and the reflection probability depending on
the weak randomness are obtained. We find that with the increase of
the random strength the ensemble-average speed of gap solitons
decreases slowly where the reduction is proportional to the variance
of the weak randomness, and the reflection probability becomes
larger. The theoretical results are in good agreement with the
numerical simulations based on the Gross--Pitaevskii equation.

This paper reports that single-layer and graded Au--TiO$_{2}$
granular composite films with Au atom content 15{\%}--66{\%} were
prepared by using reactive co-sputtering technique. The third-order
optical nonlinearity of single-layer and graded composite films was
investigated by using s- and p-polarized $Z$-scans in femtosecond
time scale. The nonlinear absorption coefficient \textit{$\beta
$}$_{\rm eff}$ of single-layer Au--TiO$_{2}$ films is measured to be
--2.3$\times $10$^{3}-$0.76$\times $10$^{3}$ cm/GW with Au atom
content 15{\%}--66{\%}. The \textit{$\beta $}$_{\rm eff}$ value of
the 10-layer Au--TiO$_{2}$ graded film is enhanced to be
--2.1$\times $10$^{4}$cm/GW calculated from p-polarized $Z$-scans,
which is about ten times the maximum \textit{$\beta $}$_{\rm eff}$
of single-layer films. Broadened response in the wavelength region
730--860\,nm of the enhanced optical nonlinearity of graded
Au--TiO$_{2}$ composite films was also investigated.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

Molecular dynamics simulation is employed to study the structural
evolution of low density amorphous ice during its compression from
one atmosphere to 2.5\,GPa. Calculated results show that high
density amorphous ice is formed at an intermediate pressure of $\sim
$1.0\,GPa; the O--O--O bond angle ranges from 83$^{\circ}$ to
113$^{\circ}$, and the O--H$\cdots$O bond is bent from 112$^{\circ}$
to 160$^{\circ}$. Very high density amorphous ice is obtained by
quenching to 80\,K and decompressing the ice to ambient pressure
from 160\,K/1.3\,GPa or 160\,K/1.7\,GPa; and the next-nearest O--O
length is found to be 0.310\,nm, just 0.035\,nm beyond the nearest
O--O distance of 0.275\,nm.

A mass of GaN nanowires has been successfully synthesized on Si(111)
substrates by magnetron sputtering through ammoniating
Ga_{2}O_{3}/Co films at 950\du. X-ray diffraction, scanning
electron microscopy, high resolution transmission electron
microscope and Fourier transformed infrared spectra are used to
characterize the samples. The results demonstrate that the nanowires
are of single-crystal GaN with a hexagonal wurtzite structure and
possess relatively smooth surfaces. The growth mechanism of GaN
nanowires is also discussed.

Shen Jun, Ge Bing-Hui, Chu Wei-Guo, Luo Shu-Dong, Zhang Zeng-Xing, Liu Dong-Fang, Liu Li-Feng, Ma Wen-Jun, Ren Yan, Xiang Yan-Juan, Wang Chao-Ying, Wang Gang, Zhou Wei-Ya

Chin. Phys. B 2008, 17 (6): 02184; doi: 10.1088/1674-1056/17/6/041
Full Text: PDF (7735KB) (
518
)

Zn_{2}SnO_{4} (ZTO) nanowires with a unique dendritic
nanostructure were synthesized via a simple one-step thermal
evaporation and condensation process. The morphology and
microstructure of the ZTO nanodendrite have been investigated by
means of field emission scanning electron microscopy (SEM), x-ray
diffraction (XRD) and high-resolution transmission electron
microscopy (HRTEM). SEM observation revealed the formation of
branched nanostructures and showed that each branch exhibited a
unique periodic structure formed by a row of overlaid rhombohedra of
ZTO nanocrystals along the axis of the nanobranch. HRTEM studies
displayed that the branches grew homoepitaxially as
single-crystalline nanowires from the ZTO nanowire backbone. A
possible growth model of the branched ZTO nanowires is discussed. To
successfully prepare branched structures would provide an opportunity
for both fundamental research and practical applications, such as
three-dimensional nanoelectronics, and opto-electronic nanodevices.

This paper reports high temperature liquid phase synthesis of Pd
nanowires using chemically modified porous anodic aluminium oxide as
template. In this synthesis process, oleic acid is used to modify the
inner wall of the pores and Pd$^{2 + }$ complex with oleylamine is
filled into the channel of the template. The complex is then reduced
to give oleylamine-capped Pd nanowires. This paper suggests that
oleic acid can improve the environment of inner wall of the pores,
leading to the formation of uniform Pd nanowires. The synthetic
process can be extended to make other types of nanowires.

The surface oxidation of silicon (Si) wafers by atomic oxygen radical
anions (O^{-} anions) and the preparation of
metal--oxide--semiconductor (MOS) capacitors on the O^{-}-oxidized Si substrates have been examined for the first time. The
O^{-} anions are generated from a recently developed O^{-}
storage-emission material of [Ca_{24}Al_{28}O_{64}]^{4+}.4O^{-} (C12A7-O^{-} for short). After it has been
irradiated by an O^{-} anion beam (0.5\mu A/cm^{2}) at
300^{0}C for 1--10 hours, the Si wafer achieves an oxide layer
with a thickness ranging from 8 to 32nm. X-ray photoelectron
spectroscopy (XPS) results reveal that the oxide layer is of a
mixture of SiO_{2}, Si_{2}O_{3}, and Si_{2}O distributed in
different oxidation depths. The features of the MOS capacitor of
x/Si> are investigated by measuring
capacitance-voltage (C-V) and current-voltage (I-V) curves. The
oxide charge density is about 6.0 \times 10^{11}cm^{2}
derived from the C-V curves. The leakage current density is in the
order of 10^{-6}A/cm^{2} below 4MV/cm, obtained from the
$I-V$ curves. The O^{-} anions formed by present method would
have potential applications to the oxidation and the
surface-modification of materials together with the preparation of
semiconductor devices.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

This paper reports that 9\,nm zincblende CrAs is grown by
molecular-beam epitaxy on InAs buffer layer. The zb-CrAs shows
ferromagnetism at room temperature and the total magnetic moment
$3.09\pm 0.15\,\mu_{\rm B}$ per CrAs unit. The temperature
dependence of zb-CrAs resistance $R$ shows metallic behaviour.

The mesoscopic quantum interference phenomenon (QIP) can be observed
and behaves as the oscillation of conductance in nano-devices when
the external magnetic field changes. Excluding the factor of
impurities or defects, specific QIP is determined by the sample
geometry. We have improved a first-principles method based on the
matrix Green's function and the density functional theory to simulate
the transport behaviour of such systems under a magnetic field. We
have studied two kinds of QIP: universal conductance fluctuation
(UCF) and Aharonov--Bohm effect (A--B effect). We find that the
amplitude of UCF is much smaller than the previous theoretical
prediction. We have discussed the origin of difference and concluded
that due to the failure of ergodic hypothesis, the ensemble
statistics is not applicable, and the conductance fluctuation is
determined by the flux-dependent density of states (DOSs). We have
also studied the relation between the UCF and the structure of
sample. For a specific structure, an atomic circle, the A--B effect
is observed and the origin of the oscillation is also discussed.

This paper studies the equilibrium structure parameters and the
dependences of the elastic properties on pressure for rutile
TiO$_{2}$ by using the Cambridge Serial Total Energy Package
(CASTEP) program in the frame of density functional theory. The
obtained equilibrium structure parameters, bulk modulus $B_{0}$ and
its pressure derivative $B'_{0}$ are in good agreement with
experiments and the theoretical results. The six independent elastic
constants of rutile TiO$_{2}$ under pressure are theoretically
investigated for the first time. It is found that, as pressure
increases, the elastic constants $C_{11}$,$ C_{33}$, $C_{66}$,
$C_{12}$ and $C_{13}$ increase, the variation of elastic constant
$C_{44}$ is not obvious and the anisotropy will weaken.

The equilibrium lattice constant, the cohesive energy and the
electronic properties of light metal hydrides LiXH_{3} and
XLiH_{3} (X=Be, B or C) with perovskite lattice structures
have been investigated by using the pseudopotential plane-wave
method. Large energy gap of LiBeH_{3} indicates that it is
insulating, but other investigated hydrides are metallic. The
pressure-induced metallization of LiBeH_{3} is found at about
120GPa, which is attributed to the increase of Be-p electrons with
pressure. The electronegativity of the p electrons of X atom is
responsible for the metallicity of the investigated LiXH_{3}
hydrides, but the electronegativity of the s electrons of X atom
plays an important role in the metallicity of the investigated
XLiH_{3} hydrides. In order to deeply understand the
investigated hydrides, their optical properties have also been
investigated. The optical absorption of either LiBeH_{3} or
BeLiH_{3} has a strong peak at about 5eV, showing that their
optical responses are qualitatively similar. It is also found that
the optical responses of other investigated hydrides are stronger
than those of LiBeH_{3} and BeLiH_{3} in lower energy ranges,
especially in the case of CLiH_{3}.

Low-temperature specific heat in a dichalcogenide superconductor
2H-NbSe_{2} is measured in various magnetic fields. It is found
that the specific heat can be described very well by a simple model
concerning two components corresponding to vortex normal core and
ambient superconducting region, separately. For calculating the
specific heat outside the vortex core region, we use the
Bardeen--Cooper--Schrieffer (BCS) formalism under the assumption of
a narrow distribution of the superconducting gaps. The
field-dependent vortex core size in the mixed state of 2H-NbSe_{2},
determined by using this model, can explain the nonlinear field
dependence of specific heat coefficient \gamma(H)$, which is in good
agreement with the previous experimental results and more formal
calculations. With the high-temperature specific heat data, we can
find that, in the multi-band superconductor 2H-NbSe_{2}, the
recovered density of states (or Fermi surface) below T_\mathrm{c}
under a magnetic field seems not to be gapped again by the charge
density wave (CDW) gap, which suggests that the superconducting gap
and the CDW gap may open on different Fermi surface sheets.

This paper reports that the ground-state energy of polaron was
obtained with strong electron-LO-phonon coupling by using a
variational method of the Pekar type in a parabolic quantum dot.
Quantum transition is occurred in the quantum system due to the
electron--phonon interaction and the influence of temperature. That
is the polaron transit from the ground-state to the first-excited
state after absorbing a LO-phonon and it causes the change of the
polaron lifetime. Numerical calculations are performed and the
results illustrate that the ground-state lifetime of the polaron will
increase with increasing the ground-state energy of polaron and
decrease with increasing the electron-LO-phonon coupling strength,
the confinement length of the quantum dot and the temperature.

We report the preparation of p-type ZnO thin films on (0001)
sapphire substrates by a combination of sol--gel and
ion-implantation techniques. The results of the Hall-effect
measurements carried out at room temperature indicate that the
N-implanted ZnO:Al films annealed at 600\du\ have converted to
p-type conduction with a hole concentration of
$1.6\times10^{18}cm^{-3}, a hole mobility of
3.67cm^{2}/V.s and a minimum resistivity of
4.80cm.\Omega$. Ion-beam induced damage recovery has been
investigated by x-ray diffraction (XRD), photoluminescence (PL) and
optical transmittance measurements. Results show that diffraction
peaks and PL intensities are decreased by N ion implantation, but
they nearly recover after annealing at 600\du. Our results
demonstrate a promising approach to fabricate p-type ZnO at a low
cost.

Hexagonal GaN epilayer grown on sapphire substrate by metal organic
chemical vapour deposition (MOCVD) is studied using Raman scattering
and photoluminescence in a temperature range from 100\,K to 873\,K.
The model of strain (stress) induced by the different lattice
parameters and thermal coefficients of epilayer and substrate as a
function of temperature is set up. The frequency and the linewidth of
$E_2^{\rm high}$ mode in a GaN layer are modelled by a theory with
considering the thermal expansion of the lattice, a symmetric decay
of the optical phonons, and the strain (stress) in the layer. The
temperature-dependent energy shift of free exciton A is determined by
using Varshni empirical relation, and the effect of strain (stress)
is also investigated. We find that the strain in the film leads to a
decreasing shift of the phonon frequency and an about
10meV-increasing shift of the energy in a temperature range from
100\,K to 823\,K.

This paper reports that a charge-transfer salt dibutylammonium
bis-7,7,8,8-tetracyanoquinodimethane [DBA (TCNQ)_{2}] has been
prepared. The temperature dependences of the DC electrical
conductivity of the DBA (TCNQ)_{2} single crystal measured along
the crystallographic a, b, and c axes are reported. The
crystal shows semiconducting behaviour and the room-temperature
conductivities are highly anisotropic (\sigma_{a} = 3.63\times
10^{-4}S/cm, \sigma_{b}= 2.84$\times 10^{-6}S/cm, and
\sigma_{c} = 1.82\times 10^{-5}S/cm). Particularly, a
sharp semiconductor to semiconductor transition has been observed
around 270 K on the resistivity curves measured under cooling and
heating. In addition, thermal hysteresis phenomena on conductivity
and differential scanning calorimetry curves are also reported.

The excitation of surface plasmons (SPs) with a strip grating at the
boundary of an unmagnetized overdense plasma has been investigated
theoretically and experimentally. An incident electromagnetic
radiation was p-polarized at the frequency of 5GHz. Experiments
showed that when the plasma density was four times higher than the
critical density with the grating present, and the SPs could be
excited at the boundary of the overdense plasma. Contribution of the
glass layer in the formation of the SP dispersion relation was
examined. When the incident electromagnetic radiation was coupled
into SPs the coupling order with the effective permittivity was
simulated qualitatively. We find that the existence of SPs at the
boundary of overdense plasma indicates that the reflection
coefficient of the incident electromagnetic radiation reaches its
minimum and even becomes total absorption. In this work the plasma
density was diagnosed by a Langmuir double probe.

To explore the mechanism of carbonyl iron flake composites for
microwave complex permeability, this paper investigates the feature
of the flakes. The shape anisotropy was certified by the results of
the magnetization hysteresis loops and the M\"{o}ssbauer spectra.
Furthermore, the shape anisotropy was used to explain the origin of
composite microwave performance, and the calculated results agree
with the experiment. It is believed that the shape anisotropy
dominates microwave complex permeability, and the natural resonance
plays main role in flake.

The magnetic properties and the magnetic entropy change \Delta S
have been investigated for Gd_{6}Co_{1.67}Si_{3} compounds
with a second-order phase transition. The saturation moment at 5K
and the Curie temperature T_{C} are 38.1\mu_{B} and
298K, respectively. The \Delta S originates from a reversible
second-order magnetic transition around T_{C} and its value
reaches 5.2J/kg.K for a magnetic field change from 0 to
5T. The refrigerant capacity (RC) of Gd_{6}Co_{1.67}Si_{3}
are calculated by using the methods given in Refs.[12] and [21],
respectively, for a field change of 0--5T and its values are 310
and 440\,J/kg, which is larger than those of some magnetocaloric
materials with a first-order phase transition.

Thermal-annealing has been widely used in modulating the oxygen
content of manganites. In this work, we have studied the effect of
annealing on the transport properties and magnetoresistance of
junctions composed of a La_{0.9}Ca_{0.1}MnO_{3 + \delta} film
and a Nb-doped SrTiO_{3} substrate. We have demonstrated that the
magnetoresistance of junctions is strongly dependent on the
annealing conditions: From the junction annealed-in-air to the
junction annealed-in-vacuum, the magnetoresistance near 0-V bias can
vary from \sim --60% to \sim 0. A possible mechanism
accounting for this phenomenon is discussed.

A combination of the iterative perturbation theory (ITP) of the
dynamical mean field theory (DMFT) and coherent-potential
approximation (CPA) is generalized to the double exchange model with
orbital degeneracy. The Hubbard interaction and the off-diagonal
components for the hopping matrix $t_{ij}^{mn} (m \ne n)$ are
considered in our calculation of spectrum and optical conductivity.
The numerical results show that the effects of the non-diagonal
hopping matrix elements are important.

The typical magnetic domains of Sm(Co_{bal}Fe_{0.25}Cu_{0.07}Zr_{0.02})_{7.4} magnets quenched
through various heat-treatment steps have been revealed by using
magnetic force microscopy (MFM). For the specimens in which the
nominal c-axis is perpendicular to the imaging plane, the domain
configurations change from plate-like for the as-sintered magnet to
corrugation and spike-like for the homogenized one, and then to a
coarse and finally to a finer domain structure when isothermally aged
at 830\du\ and then annealed at 400\du. However, only plate-like
domains can be detected on the surfaces with the nominal c-axis
parallel to the imaging plane. The finer domain (so-called
interaction domain) is a characteristic magnetic domain pattern of
the Sm--Co 2:17-type magnets with high coercivities. Domain walls in
a zigzag shape are revealed by means of MFM in final bulk Sm--Co
2:17-type sintered magnets.

8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Three new vorticity vectors have been proposed by Gao {\em et al} to
study the two-dimensional tropical convection. In the present paper,
phase relations between surface rain rate and the vorticity vectors
are analysed with the calculations of lag correlation coefficients
based on hourly zonally-averaged mass-integrated cloud-resolving
simulation data. The cloud-resolving model is integrated with the
vertical velocity, zonal wind, horizontal thermal and moisture
advections, and sea surface temperature observed and derived from
tropical ocean global atmosphere -- coupled ocean atmosphere response
experiment (TOGA-COARE) for 10 days. Maximum local increase of the
vertical component of the convective vorticity vector leads maximum
surface rain rate by 2 hours mainly due to the interaction between
vorticity and zonal gradient of ice heating. While maximum local
increase of the vertical component of the moist vorticity vector
leads maximum surface rain rate by 2 hours mainly because of the
interaction between zonal specific humidity gradient and zonal
buoyancy gradient. And the maximum local decrease of the zonal
component of the dynamic vorticity vector leads maximum surface rain
rate by 2 hours mainly due to the interactions between vorticity and
vertical pressure gradient as well as vorticity and buoyancy.

Based on physical backgrounds, the four time series of the Guliya
(Tibetan plateau) ice core (GIC) \textit{$\delta $}$^{18}$O, and
three natural factors, i.e. the rotation rate of earth, sunspots, and
El Nino--Southern Oscillation (ENSO) signals, are decomposed into two
hierarchies, i.e. more and less than 10-year hierarchies
respectively, and then the running $t$-test is used to reanalyse the
data before and after filtering with the purpose of investigating the
contribution of natural factors to the abrupt climate changes in the
last one hundred years. The results show that the GIC \textit{$\delta
$}$^{18}$O evolved with a quasi-period of 7--9 years, and the abrupt
climate changes in the early 1960s and in the period from the end of
the 1970s to the beginning of the 1980s resulted from the joint
effect of the two hierarchies, in other words, the two interdecadal
abrupt changes of climate in the last one hundred years were global.
The interannual variations of ENSO and sunspots were the important
triggering factors for the abrupt climate changes in the last one
hundred years. At the same time, the method of Information Transfer
(IT) is employed to estimate the contributions of ENSO signals and
sunspots activities to the abrupt climate changes, and it is found
that the contribution of the interannual variation of ENSO signals is
relatively large.

A simple and efficient screening model for studying the effects of
superstrong magnetic fields (such as those of magnetars) on
thermonuclear reaction rates on magnetar surfaces is proposed in
this paper. The most interesting thermonuclear reactions, including
hydrogen burning by the CNO cycle and helium burning by the triple
alpha reaction, are investigated on the surface of magnetars. We
find that the superstrong magnetic fields can increase the
thermonuclear reaction rates by many orders of magnitude. The
enhancement may have a dramatic effect on the thermonuclear runaways
and bursts on the surfaces of magnetars.

We have studied the Hawking radiation of the Kerr--Newman--Kasuya
black hole via gauge and gravitational anomaly in the dragging
coordinates. The fluxes of the electromagnetic current and the energy
momentum tensor for each partial wave in two-dimensional field are
obtained.

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