1994年, 第21卷, 第1期　
刊出日期：1994-01-30

  

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  Thermoelectric Coefficients of Silicon MOSFETS in Quantizing Magnetic Field

  G. QIN, P. N. Butcher

  理论物理通讯. 1994, 21(1): 1-8.

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  The phonon drag and electron diffusion contribution to the tensor M which determines 3 the heat flux U = M·E is calculated for a silicon MOSFETS in a perpendicular magnetic field B. We used nearly the same theoretical formalism as Ref [6], but improvements are made in several respects. First of all the dielectric function of Fermi-Thomas approximation which has been proved to result in overscreening of the interaction is replaced by rigorous Lindhard-type dielectric function to take account of the screening between electrons and phonons. Secondly the contributions of localized electrons are separated from those of the free state electrons which are the only part that contributes to both conductivity tensor and magnetothermopower tensor. The calculated M_yx and S_xx reveal magneto-oscillationsoriginating Gom oscillations in the density of states at the Fermi level. At T = 5.02 K, our new results show that the diffusion components of thermopower are negligibly small compared with those due to phonon drag. All the theoretical values of M_yx, S_xx and S_yx are in accordance with the experimental data better than previous theoretical results.
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  Calculations of Local Distortions Around the Orthorhombic Gd³⁺ : M⁺: CaF₂ Complexes

  Y. Y. YEUNG

  理论物理通讯. 1994, 21(1): 9-16.

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  A reliable lattice relaxation model is developed in detail for calculating the ionic positions of Gd³⁺ at orthorhombic sites in CaF₂ with a nearby charge-compensating M⁺ ion (M=Li,Na, KJ Rb and Cs). In this model, all the ionic displacements induced by the Gd³⁺ and M⁺ impurity ions are treated using the discrete atomistic basis. In comparison with some experimental data on the ionic shifts in the Gd³⁺: M⁺: CaF₂ complex, our calculated results are found to be much better than the previous calculations based on the semi-discrete approach with a dielectric continuurn approximation.
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  Hydrogenic Impurity States in Lateral-Surface-Modulation Quantum Wires

  Zhen-Yan DENG, Hong SUN, Shi-Wei GU

  理论物理通讯. 1994, 21(1): 17-24.

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  We calculate hydrogenic impurity binding energy in quasi-one-dimensional GaAs/AIAs quantum wires with periodical lateral surface structure by making use of a variational approach. By a coordinate transformation, the structured interfaces of the wires are transformed into planar ones so that the boundary conditions of the electronic wave functions can be satisfied exactly on the interfaces. The dependence of the binding energies on the positions of the impurities and on the lateral surface structures is studied.
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  Scaling Investigations on Dynamics of a Homogeneity-Fractal Mixed Structure

  Yu SHI, Chang-De GONG

  理论物理通讯. 1994, 21(1): 25-28.

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  Several dynamical properties on a homogeneity-fractal-mixed structure are explored by scaling methods. We discuss random diffusions, vibrational excitations and its scattering by structural irregularities.
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  Mean Field Theory of Ising Model on Sierpinski

  Xiang-Dong MI, Z. R. YANG

  理论物理通讯. 1994, 21(1): 29-34.

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  We study Ising model on Sierpinski carpets by using mean field theory. We find a phase transition at T_c > 0 which is dependent on the geometrical factors. The critical exponents are calculated and found to be the same as the values for translationally invariant lattices.
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  A q-Deformed osp(1,2) Superalgebra and Its Coherent States

  Le-Man KUkNG, Gao-Jian ZENG, Fa-Bo WANG

  理论物理通讯. 1994, 21(1): 35-42.

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  In this paper we present a q-deformed osp(1, 2) superalgebra, construct a type of coherent state representations and obtain a q-differential realization for the q-deformed superalgebra.We also study some quantum optical properties of the q-deformed osp(1, 2) coherent states.
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  The Critical Behaviour of Conductivity for Some Two-Dimensional Fractals

  Guo-Ce ZHUANG, Kai-Lun YAO, Yong SHI

  理论物理通讯. 1994, 21(1): 43-46.

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  The critical behaviour of conductivity for some two-dimensional fractals is studied by experiments. The results show that the conductivity exponent is fractal dimensionality dependent with exponential scaling behaviour but is fractal material independent.
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  A q-Analogue of Normal Ordered Operation

  Lei MA, Zhong TANG, Yong-De ZHANG

  理论物理通讯. 1994, 21(1): 47-52.

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  In this paper the operation of q-normal ordered product is realized in q-analogue bosonic oscillators. The expression of the vacuum projective operator in the form of q-operators is obtained, some initial applications about this operation are also given.
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  Multichannel Coupled Nonlocal Interactions and Generalized Levinson Theorem

  Zi-Li CHU, Lian-Yuan CHU

  理论物理通讯. 1994, 21(1): 53-58.

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  The T matrix is determined by the generalized Lipprnann-Schwinger equations with the multichannel coupled nonlocal separable potential of arbitrary rank N, and for the potentials, a generalized Levinson theorem is proved with a new method.
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  Relativistic Effective Interaction

  Zhong-Yu MA, Bao-Qiu CHEN

  理论物理通讯. 1994, 21(1): 59-68.

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  In analogy with the idea of the effective interaction commonly used in the nonrelativistic approach, the relativistic effective .interactions are adopted to incorporate the relativistic Brueckner-Hartree-Fock (RBHF) results in the relativistic mean field approach (RMF) or relativistic Hartree-Fock approach (RHF). It is desired to remedy the deficiencies of RMF and RHF without losing the features of the relativistic G matrix and at the same time retain the simplicity. The relativistic effective interactions are used to describe the ground state properties of nuclei and medium-energy nucleon-nucleus scattering in this paper.
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  Influence of the In-Medium Quark Mass on the K⁺-Nucleus scattering

  De-Fen MIN, En-Guang ZHAO, Ping-Zhi NING

  理论物理通讯. 1994, 21(1): 69-72.

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  The influence of density-dependent quark masses, based on the Nambu-Jona-Lasinio model, on K⁺-nucleus scattering is investigated. Introduction of this density dependence is found to be a possible explanation for the missing theoretical K⁺-nucleus cross section
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  Chiral Symmetry Breaking as a Phase Transition in QED Plus NJL Model

  Guang-Jiong NI, Ji-Fang YANG, Dao-Hia XU, Su-Qing CHEN

  理论物理通讯. 1994, 21(1): 73-84.

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  The chiral symmetry breaking (CSB) of massless &ED is studied analytically and then numerically by introducing a Nambu-Jona-Lasinio (NJL) term. We use the method of relativistic canonical transformation and random phase approximation to find the criterion for CSB (i.e., the condensation in vacuum) and the accompanying elementary excitations. The role played by NJL term, the scale anomaly and the meaning of critical point (α_c≈1.5) are discussed.
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  Higgs as Gauge Fields on Discrete Groups

  Hao-Gang DING, Han-Ying GUO, Jian-Ming LI, Ke WU

  理论物理通讯. 1994, 21(1): 85-94.

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  We complete the construction of the gauge theory on discrete groups including fermions in the spirit of non-commutative geometry. We show that a simple Higgs field is such a gauge field with respect to Z₂-gauge symmetry over M⁴ and the Yukawa coupling between Higgs and fermions is automatically introduced via minimum coupling principle. We also present an Abelian toy model.
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  Distribution Function of Polarized Proton

  Zai-Xin XU, Jun SHEN

  理论物理通讯. 1994, 21(1): 95-100.

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  The region of allowed values of quark and gluon spin densities in a proton is discussed. The helicity difference distributions of the constituents which can fit the existent data for g₁^p are constructed and the significant differences between the results fiom our distributions and from other models at small x region (< 10^-1) are shown.
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  Simplified Ideal MHD Normal Mode Equations for Toroidal Axisymmetric Plasmas

  Bing-Ren SHI

  理论物理通讯. 1994, 21(1): 101-106.

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  The ideal MHD normal mode equations for general toroidal axisymmetric plasmas can be significantly simplified by properly treating the compressibility team limiting cases: and c_s is the plasma sound velocity.These equations describing the general global modes (the low n, m mode) contain only two scalar functions. For tokamak plasmas, a further simplification, the shear Alfven approkimation, is introduced. It makes possible to describe the global mode by a simplified eigenmode equation with only one scalar function. This eigenequation, similar to the reduced tokamak equations widely used in recent literatures, provides a unified way to analyze the kink, Alfven spectrum and MHD TAE modes.
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  Nonlinear Responses of the Collisional Rayleigh-Taylor Modes to a Neutral Atmospheric wave in Equatorial F Region Ionosphere

  Ying WU

  理论物理通讯. 1994, 21(1): 107-112.

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  An analytical investigation of the asymptotic behavior and thk bistability of coherent 20 mode coupling among collisional Rayleigh-Taylor modes in equatorid F region ionosphere with one mode forced by a neutral atmospheric wave (as a pump) where the linear growth rate γ of the 'forced mode is much larger than its frequency. The results show that no stable asymptotic state exists for a nonzero w and the pump amplitude below a critical value depending on ω, where ω is the frequency detuning between the pump and the forced mode, otherwise, there exists at least one stable asymptotic state, bistability may occur only when ω satisfies 1/4 ≤ (ω/γ)² < 1/3. The bistable transition leads to the substantial energy variations of the collisional Rayleigh-Taylor modes, and its occurrence requires the relative density perturbation caused by the neutral atmospheric wave on the order of a few percent for the typical ionospheric parameters.
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  Effect of Inelastic Scattering on the Electron Transport in a One-Dimensional Electron Interferorneter

  Jian-Xin ZHU, Bai-Geng WANG, Qi JIANG, Chang-De GONG

  理论物理通讯. 1994, 21(1): 113-118.

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  Using the Büttiker formalism, we calculated the conductance of a one-dimensional interferometer,which consists of two quantum point contacts (QPC's) and a cavity sandwiched between them, in the presence of a phase randomizing scatterer located at the lower boundary of the cavity. The results show that a little inelastic scattering will completely destroy the formation of discrete zero-dimensional states, but the Aharonov-Bohrn-type oscillations can still take place, which are influenced by the inelastic scatterer.
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  Unity Operator in Fock Space

  Lei MA, Si-Xia YU, Zhong TANG, Yong-De ZHANG

  理论物理通讯. 1994, 21(1): 119-120.

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  A kind of unity operators in Fock space has been studied in this letter.
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  The Minimal Cqupling of Charged spin-3/2 Fields to an Extended Abelian Gauge Model

  R. M. Doria, J. A. Helayël-Neto, S. Mokhtari

  理论物理通讯. 1994, 21(1): 121-124.

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  Charged spin-3/2 fields are coupled to an extended gauge model without the total suppression of the vector degrees of freedom which usually takes place as a consequence of simultaneously imposing the Maxwell and Rarita-Schwinger U(1) symmetries.
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  Probing the Flavor Asymmetric Nucleon Sea with Weak Currents

  Mujahid Kamranl

  理论物理通讯. 1994, 21(1): 125-128.

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  NMC has recently shown that the proton contains an excess of dd sea pairs as compared to uu sea pairs. We form appropriate combinations of quantities in v and v DIS which are sensitive to this flavor asymmetry of the sea. Estimates of the sensitivity of these quantities to the flavor asymmetry of the sea are obtained.