Vol. 42, No. 5 (1993)
1993-03-05
GENERAL
1993, 42 (5): 691-698.
doi: 10.7498/aps.42.691
Abstract +
The SUq(2) coherent state is constructed by making use of the q- deformation harmonic oscillators realization of the SUq(2) quantum algebra. It is shown that the basis functions of the SU, (2) quantum algebra is orthogonal. The completeness and normalizing property of the SUq(2) coherent state is studied. We point out that the coherent property of the SUq(2) co-herent state is affected by q parameter, and show more generalility than the usual SU(2) co-herent state.
1993, 42 (5): 699-704.
doi: 10.7498/aps.42.699
Abstract +
The exact solution to a velocity-dependent forced quantum anharmonic oscillator is de-rived by using the integral oprators and iteration method. The time development of the dis-placement and momentum operators of the anharmonic oscillator is given. These operators are represented as a Laplace transform and a subsequent inverse Laplace transform of suitable functionals.
1993, 42 (5): 705-710.
doi: 10.7498/aps.42.705
Abstract +
For a quantum system with time dependent boundary conditions, it is shown that the ef-fective Hamiltonian can be constructed in a simple way without any geometric treatemnt. In this paper the effective Hamiltonian, constructed in the above way, of quantum particle in a spherical box of varying radius is used to calculate the Berry phase of the wave function. We found that the effective Hamiltonian and original one are formally related with a static gauge transformation, the quantum states of the two Hamiltonians differ by a Berry phase.
1993, 42 (5): 711-720.
doi: 10.7498/aps.42.711
Abstract +
A both nondifferentiable (or discontinuous ) and noninvertible one-dimensional map can display a new type of intermittency. The mechanism of it is that a stable fixed point collides with the nondifferentiable of discontinuous point of the map and then disappears. This type of intermittency can happen in the case when the absolute eigenvalue of the linearised map near the fixed point equals any number smaller than 1 before the intermittency. Therefore, it can appear suddenly in any part between a period-doubling cascade, interrupt the cascade and lead to chaos. In the intermittent time plot after disappearence of the stable fixed point the dura-tion of the laminar phase follows a logarithmic dependence on the distance between a control parameter value and its critical number. This new scaling law is independent of the details of the map. We believe that this new type of intermittency should exist in many practical sys-tems.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
1993, 42 (5): 721-726.
doi: 10.7498/aps.42.721
Abstract +
By use of the Kustannheimo-Stiefel transformation, the problem of a four-dimensional covariant harmonic oscillator can be transformed to that of a three-dimensional hydrogen atom with constraint. On this basis, the difficulty of the excitation of the time degree of freedom can be avoided naturally and the mass-squared formula for mesons can be obtained.
ATOMIC AND MOLECULAR PHYSICS
1993, 42 (5): 727-734.
doi: 10.7498/aps.42.727
Abstract +
From comparing the energy expression within the quantum defect theory (QDT) and the theory of the weakest bound electron potential model (WBEPM), we try to introduce a ad-justing coefficient k which can reflect the screening effects in the real atomic or ionic system. The calculation of expectation values of the radius and others shows that the coefficient k in-troduced not only makes accurate the describing of Rydbery series when using the parameters of isoelectronic series ; but also reveals the difference and relation between these two series. Another main content of this paper is about the adjustment of the number of nodes in eigen-functions of the valence electrons for atoms.
1993, 42 (5): 735-740.
doi: 10.7498/aps.42.735
Abstract +
Following the method of the adjusting coefficient k we introduced and using the simple analytical wavefunction within the weakest bound electron potential model (WBEPM), the transition results of each member in the isoelectronic series only vary with its nucleus charge number Z. So we can conveniently calculate the transition probabilities of Li I and the oscil-lator strengths of the 3-electron series. The comparisons with other methods show that not only the regularity of transitions in the isoelectronic series is reflected, but also a more accu-rate result could be obtained. The WBEPM theory with adjusting coefficient k can provide good trial wavefunctions for detailed atomic calculations, particularly for the study of isoelectronic series.
1993, 42 (5): 741-749.
doi: 10.7498/aps.42.741
Abstract +
The least-squares fitting of the observed energy levels to the Watson' s Hamiltonian con-stants of water vapor vibrational states (202), (122), and (004) had been performed. Using these constants and the revised quantum Fourier transformation (namely QFT*) method, we calculated the N2-broadened widths of the observed absorption lines for (202) band. Also we obtained the N2-broadening widths and temperature dependences of lines in the R(l ,1) branch of (202), (122), and (004) bands. The agreement between calculation and experiment show that the fitting to the Hamiltonian constants is reasonable and the QFT* method can be ap-plied to calculate the collision broadening of water voapor in the visible region. In addition, the calculated results indicated that in the visible region the collision broadening and line-width temperature dependence vary with the rotational and vibrational quantum numbers, and the maximum values of these two parameters might be two times as large as the corresponding minmum value.
CLASSICAL AREA OF PHENOMENOLOGY
1993, 42 (5): 750-756.
doi: 10.7498/aps.42.750
Abstract +
Starting from the relativistic motion equation of a single particle,the motion constants were obtained. And then by using these motion constants a distribution function of the beam particles was constructed which satisfies the Vlasov equation. The beam temperatures and the energy broadening of a relativistic charged-particle beam in axially symmetric electric- and magnetic-fields have been calculated by using the distribution function,and the weakly and strongly relativistic approximations have also been discussed respectively.
1993, 42 (5): 757-761.
doi: 10.7498/aps.42.757
Abstract +
The orthonormal eigenstates of operator aq2 are constructed. It is shown that they form a complete Hilbert space.
1993, 42 (5): 762-768.
doi: 10.7498/aps.42.762
Abstract +
A simplified computational approach of free-electron lasers is proposed,which is suitable to the operation on micro-computers. The saturation output laser powers from the simulation on a micro-computer (AST386/33L)by means of this simplified approach are in agreement with the data measured in the MIT's experiment.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1993, 42 (5): 769-774.
doi: 10.7498/aps.42.769
Abstract +
By considering the lower hybrid wave trajectory,spectrum variation and power deposition in HT-6B tokamak plasma,we calculated the currents driven with different plasma density. The results show that there exists a density window for lower hybrid wave current drive (LHCD) ,i. e ,LHCD would be achieved only within a certain range of plasma density. The ex-planation of such a density window is given and the parameters option is also discussed.
1993, 42 (5): 775-784.
doi: 10.7498/aps.42.775
Abstract +
The relativistic electron cyclotron wave dispersion relation has been derived analytically with the electron distribution function also a relativistic one. The singularity which is in-evitable in these problem has been calculated analytically without imposing any condition. So the formula obtained here can be directly applied to the general situation of wave propagation and absorption. It provided a convenient formula for the study of high temperature plasma electron cyclotron wave.
1993, 42 (5): 785-791.
doi: 10.7498/aps.42.785
Abstract +
In the paper, we present the experimental results about the relationship between the plasma parameters' distribution and its target structure. The diagnostic results show that the characteristics of electron temperature and electron density distributions depend strongly on the target structure. The ionization state distributions of different targets are also discussed and compared with the theoretical calculated results for a simple model.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1993, 42 (5): 792-797.
doi: 10.7498/aps.42.792
Abstract +
With a local potential of site-impurity in the frame work of the SSH model, the Coulomb effect of the dopant ions on the vibrational modes around the charged-soliton in doped poly-acetylene has been studied. The calculated results showed that the Goldstone theorem will be destroyed and the translation mode g1 will be pined by the dopant potential. At the same time, a new even-parity mode g′ 1 has been found. The appearance of g1 and g′1 interpret well the broad peak at 930 cm-1. In addition, other localized modes have also been discussed.
1993, 42 (5): 798-802.
doi: 10.7498/aps.42.798
Abstract +
The non-ferroelectric two-component piezoelectric single crystal Al0.088Ga0.12PO4 grown from solution by slow heating method is obtained. We determine the structure of the single crystal by results of three kinds of measurements. Finally, the electro-elastic constants of this single crystal as a new kind of piezoelectric material are given.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1993, 42 (5): 803-808.
doi: 10.7498/aps.42.803
Abstract +
A new approach for studying the electronic properties of the Ⅱ-Ⅵ compounds is presented , in which the atoms in a cluster is divided into the inner ones and boundary ones, the influence of the charge transfer on the environmental potential produced by the ion lattices outside the cluster is taken into account. The occupation number of the cluster molecular orbitals is calculated by a modified DV-SCC method with a new environmental potential. The net charges and the charge transfer of the clusters TM: ZnSe are investigated from the calculated electronic structure parameters. Some of new regularity, the behaviour and concept, due to the interaction between the transition-metal ions and ligand ions are discussed in brief.
1993, 42 (5): 809-816.
doi: 10.7498/aps.42.809
Abstract +
The stable ordered structures of (GaAs)1-xGe2x system have been studied, using the probability wave theory of the atomic configuration (PWAC). Based on the determination of the ordered structures, the electronic structures of five typical stable ordered structures for x = 0.5 are investigated by the use of first principle self-consistent LMTO method. The calculated results show that the electronic properties of different ordered structures can be quite different. The more Ga-Ge and Ge-As atomic bonds in unit cell of ordered structures are, the more possible the ordered structures are expected to exhibit a metallic character.
1993, 42 (5): 817-823.
doi: 10.7498/aps.42.817
Abstract +
The deep levels of P-HEMT structure grown by MBE have been studied using DLTS technique. DLTS Spectra of samples show that high temperature electron traps, having larger capture cross sections and concentrations, are measured in n-AlGaAs layer of P-HEMT structure. These traps may correlate strongly with oxygen content of n-AIGaAs layer and be responsible for electrical parameters of P-HEMT structure. The experimental results also show that DLTS technique may be a tool of optimisation design of practical devices.
1993, 42 (5): 824-831.
doi: 10.7498/aps.42.824
Abstract +
The optical constants were calculated for coherently strained alloys GexSi1-x on Si (001) substrates with tight - binding method. The effects of strains on the electronic energy band structures are taken into account by modifying the tight-binding parameters according to the variations of the bond angle cosines and the bond lengths. For the changes of the bond lengths, an empirical scaling rule is used, in which the scaling indexes are determined through fitting the calculated values of deformation potential constants to their experimental values for Ge and Si. The momentum matrix elements in the formula for calculating the imaginary part of dielectric constants are determined by fitting the ε2 of Ge and Si. The calculated results for the optical constants , including the imaginary part of dielectric constant, the refractive index, the absorptance and the reflectance, are given both for the strained alloys and bulk alloys GexSi1-x as x=0.2 and 1. By comparison of them, the effects of strains on the optical constants are discussed.
1993, 42 (5): 832-839.
doi: 10.7498/aps.42.832
Abstract +
We have studied behaviour of a-Ge/Pb layers after annealing at different temperatures. We obtained: (1) Pb induced amorphous Ge to crystalize. (2) There are two diffusion mecha-nism in the annealing a-Ge/Pb layers. (3) For a-Ge/Pb 200nm/100nm layers, preferred orientation Pb are recrystalllized in annealing. We also explained abnormal behaviour of resistivity during the annealing of layers.
1993, 42 (5): 840-846.
doi: 10.7498/aps.42.840
Abstract +
The NdxFe1-x amorphous thin films with x=0.06-0.80 were prepared at 77 K by flash evaporation. The results show that the amorphous films are stable at room temperature when 0.192 and T untill the crystallization occurs. The crystallization of the amorphous films can not be completed at a certain fixed temperature but over a temperature range.
1993, 42 (5): 847-852.
doi: 10.7498/aps.42.847
Abstract +
The effect of grinding on superconductors of Y-123 and Bi(Pb)-2223 phases and phase formation have been studied by means of X- ray diffraction, differential thermal analysis, scanning electron microscope and measurements of the superconductivity. The experimental results show that there is significant difference of grinding effect on Y-123 and Bi(Pb)-2223 phase superconductors. Grinding causes a change of crystalline state to amorphous one for Bi(Pb)-2223 phase superconductor. The effect of the mechanical strain from preparing process and accident on superconductivity of material should be taken into consideration.
1993, 42 (5): 853-858.
doi: 10.7498/aps.42.853
Abstract +
In this paper,the Ising model with two-body anisotropic interactions and three-body interactions on union Jack lattice is solved by free-fermion approximation. We have obtained its free energy, spontaneous magnetisation and the equation of critical points. When the interaction coefficients are simplified as in a square lattice Ising model, the same solusion as Onsager's is obtained.
1993, 42 (5): 859-863.
doi: 10.7498/aps.42.859
Abstract +
EPR spectra of V4+-doped single crystal (V4+/KTP) were observed in X band at room temperature. The analysis on the spectra shows that the V4+ ions may occupy two kinds of crystallographically diffrent sites, each kind of sites contains four magnetically nonequivalent but crystallographically equivalent sites. The angular varitions of EPR hyperfine lines were measured with the external magnetic field in three mutually perpendicular planes. The principal values and direction cosines of the principal axes of the g and A tensors, were computed by a least-squares fitting procedure. These main results reveal that the V enters the lattice to substitute for the Ti ion of KTP to form V site with a tetragonally distorted octahetral symmetry. The orientations of all eight Ti ion sites substituted in an unit cell of KTP have been determined.
1993, 42 (5): 864-866.
doi: 10.7498/aps.42.864
Abstract +
The photoluminescence of Be-doped GaAs quantum wells with width of 10 nm was measured at 4.2 K. The doping concentration is about 1×1017 and 5×1018cm-3. The results showed that the product of the density of states of acceptors and the probability of transition from conduction subband n=l to neutral acceptors at the well center is larger than that near the interface of GaAs and AlGaAs. In addition, the ionization energy of acceptors is decreased as doping concentration is increased. It is due to band-gap narrowing with the doping concentration of p-type GaAs.
