1995年, 第24卷, 第2期　
刊出日期：1995-09-15

  

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  Effect of Induced Gauge Field in Jaynes-Cummings Atom with Space-Dependent Coupling

  En-Ke TIAN, Chang-Pu SUN

  理论物理通讯. 1995, 24(2): 129-132.

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  The effect of the motion of mass center of a two-level atom on its transition.in a quantized radiation field is studied in this paper by generalizing the Jaynes-Cupmings model to include the coupling depending on space degrees of freedom. As an additional geometrical phase- Berry's phase in the oscillation, the effect of the induced gauge field resulting from the Born- Oppenheimer (BO) approximation explicitly exists in the transition probability between the up and down states of atomic quasispin. It is shown that when the atom's kinetic energy is small enough that the BO adiabatic approximation holds for the case with small atom's momentum or large detuning, the adiabatically approximate solutions are applicable and it is possible to localize an atom in the cavity.
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  The Jahn-Teller Instability of the Negatively Charged C₆₀ Molecules

  Feng CHEN, He-Ping YING, Da-Dong YAN, Wen-Zhu LI

  理论物理通讯. 1995, 24(2): 133-138.

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  The linear 2 × (E + T) Jahn-Teller problem is relevant to the instability of C₆₀ molecules in threefold degenerate states when the E and T modes become degenerate. An isostationary function method is generalized to identify all extremes on the corresponding potential energy surface for different occupation numbers. For the C₆₀ molecules, the extremes are found to form an equipotential minimal energy trough for all occupation cases. For a nondegenerate case, two different coupling regimes are possible, favoring either pure tetragonal or pure trigonal distortions, depending upon the correponding Jahn-Teller energies.
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  The Higher-Order Approximation in General Theory of Self-consistent Field Beyond Hartree-Fock

  Huan-Wu PENG, Jian-Hua CHEN, Hui-Sun KUANG, Xian-Ai CHENG

  理论物理通讯. 1995, 24(2): 139-142.

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  In this paper, the higher-order approximation in the general theory of self-consistent field is presented by the Wick's theorem, and the solution of equations is discussed.
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  Quantum Description of the Magnetic Polaron in Antiferromagnetic Semiconductors

  Chao-Fan YU, Bing-Kun XIE

  理论物理通讯. 1995, 24(2): 143-150.

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  On the basis of exchange interaction of impurity electrons with localized moments, the magneticpolaron Hamiltonian for antiferromagneticsemiconductorsis derived. By themethod of canonical transformation, the properties of magnetic polarons for the intermediate-coupling case are discussed. Especially in the strong-coupling case, those properties are considered by using the generalized Landau-Pekar method, and the analytical results such as self-energy, effective mass and the space location are given in the long wave-length approximation.
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  Structure of Flux Line Lattices in Tilt Magnetic Fields of Anisotropic Superconductos

  Hong-Ru MA

  理论物理通讯. 1995, 24(2): 151-158.

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  We study here, by the minimization of the total energy of flux line systems, the zero temperature structure of flux lines of uniaxial anisotropic superconductors in a tilt magnetic field. The anisotropic London model is used and an efficient method is developed to make the total energy calculation manageable. Two degenerate structures are found, one is a deformed triangular structure and the other is a superlattice with three lines per unit cell.
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  Effects of Boundary Conditions and Relative Dimensions of a Solution System on Scaling Laws

  Zheng-Yi XU, Chong-Ru HUO, Pei-Wen GE, Zhen-He ZHU

  理论物理通讯. 1995, 24(2): 159-166.

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  A two-dimensional hydrodynamic model is employed to analyze the characteristics of crystal growth from solution with only the variation of the solution density caused by the temperature change taken into account. In that case all the characteristics of the solution system only depend on three numbers: the Rayleigh number Ra, the Prandtl number Pr and the Schemidt number Sc. In certain regions of the parameter (Ra, Pr and Sc) spaces, some scaling laws are generated: the scales of the temperature distribution index S_θ, the concentration distribution index S_ø (see text), the fluid velocity and the growth rate of crystal are given by power functions of Ra, Pr and Sc. The effects of the geometrical shape and the boundary condition of the solution system on the scaling laws are studied. When the ratio X of the height to the length of the solution system changes, the scaling laws are still valid and only the coefficients of power functions are changed, which are also power functions of A. The scaling laws are valid both under the isothermal temperature boundary condition and the adiabatic boundary condition at the surfaces of the top and the bottom sides of the solution system. The only difference is that the ratio of S_θ to Ra is greater for the latter than for the former. In certain ranges of Ra, there are no differences between the other power functions for the two cases.
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  An Equivalence Between the BEG Model and an Ising Model with Cross and Four-Spin Interactions on Square Lattice

  Xiang-Dong MI, Z.R. YANG

  理论物理通讯. 1995, 24(2): 167-170.

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  An equivalence is found between the BEG model and an Ising model with cross and four-spin interaction on square lattice under a well-known restriction e^K cosh J = 1.
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  Formal Series Symmetry Approach for a Generalized Type of High Dimensional Models

  Xian-Min QIAN, Sen-Yue LOU

  理论物理通讯. 1995, 24(2): 171-176.

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  A formal series symmetry formula is given for a quite generalized partial differen tial-difference vector equation. The details about the symmetries of the KP equation are restudied by means of the potential KP equations.
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  Nonclassical Symmetry Reductions for the Integrable Super KdV Equations

  Chang-Zheng QU

  理论物理通讯. 1995, 24(2): 177-184.

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  Using the direct method introduced by Clarkson and Kruskal (CK), we obtain similarity reductions of the integrable super Kd V equations. The group explanations of the results are also given.
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  Linear Quantum Transformation Theory of Multi-Mode Bosons and Its Application to Calculation of Partition Function

  Si-Xia YU, Yong-De ZHANG

  理论物理通讯. 1995, 24(2): 185-190.

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  In this paper, we present a linear quantum transformation theory in the m-mode boson Fock space, and give a formula that shows how a transformation operator changes its exponential form to its normal ordered form. As an application we evaluate the partition function of a general quadratic system without any information of the energy levels of the system by using our transformation theory.
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  Coherent States and Some Realizations of the Quantum Algebra SU_q(1, 1)

  Ren-Shan GONG

  理论物理通讯. 1995, 24(2): 191-196.

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  For the quantum algebra SU_q(1,1), a q-analogue of the SU(1,1) coherent statesis constructed. These coherent states are shown to satisfy a unity resolution relation. With the help of coherent states the q-deformed Dyson and Holstein-Primakoff realizations of the quantum algebra SU_q(1,1) are also obtained.
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  Unified Treatment of Systematics for Even-Even Nuclei with A≥70

  Yu-Min ZHAO, Yan CHEN

  理论物理通讯. 1995, 24(2): 197-208.

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  By the concept of effective boson numbers, systematics of E₂₁+E₄₁+E₆₁+, R=E₂₁+/E₄₁, B(E2, 0₁⁺→2₁⁺) and Q₀ for even-even nuclei with A≥70 are presented. New features of energy spectra are noticed and an intuitive understanding is given.
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  σ-ω Mixing for the Collective Excitation Spectra of σ, ω Mesons in Nuclear Matter

  Liang-Gang LIU, Lian HU

  理论物理通讯. 1995, 24(2): 209-212.

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  We study σ-ω mixing on the σ and ω propagators in two ways. The collective excitation spectra of σ,ω mesons are calculated by using these propagators. We find that the two ways of σ-ω mixing give very similar collective excitation spectra in the time-like region.
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  Two-Dimensional Noncommut at ive Analysis, Maurer-Cartan Equation and Riemann-Hilbert Problem

  Zai-Zhe ZHONG

  理论物理通讯. 1995, 24(2): 213-220.

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  In this paper a new analytic method is given, in which the quantum group theory and the classical analysis are fused into a noncommutative analysis. In this noncommu tative analysis the Maurer-Cartan equation on the quantum plane can be solved. The dassical Riemann-Hilbert problem can be extended to the noncommutative analysis, and by using this Riemann-Hilbert problem, some nontrivial new solutions of the quantum Maurer-Cartan equation can be generated.
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  Normally Ordered Operator Realization of U(1/1) Supergroup and Super-Jaynes-Cummings Model

  Hong-Yi FAN, Qun LEE

  理论物理通讯. 1995, 24(2): 221-226.

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  By making use of the technique ofintegration within an ordered product (IWOP) of operators and the bosonic and fermionic coherent states we derive the normally ordered operator realization of U(1/1) supergroup. Its application in calculating the superpartition function of the supersymmetric Jaynes-Cummings model is demonstrated. The antinormally ordered realization of U(1/1) is also obtained.
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  The Hard Thermal Loops and the Self-consistent Calculation of the Effective Potential

  De-Fu HOU, En-Ke WANG, Jia-Rong LI, Lian-Shou LIU

  理论物理通讯. 1995, 24(2): 227-232.

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  By developing the "tadpole graph method" including the resummation of the hard thermal loops in the tadpole diagrams, a self-consistent method is proposed in the calculation of effective potential. It is shown that the calculated effective potential at finite temperature in the Higgs model is more selEconsistent than the naive calculation. The two difficulties encountered in the naive calculations of the effective potential disappear naturally, The calculated results indicate that the symmetry restoration transition is of the first order.
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  Effective Mean-Field Theory Based on Cumulant Expansion: A New Approach Method Order by Order

  Ying AN, Yong-Xin SONG

  理论物理通讯. 1995, 24(2): 233-238.

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  We propose in this paper an effective mean-field theory, which makes the calculation for any observable being performed in a general form of cumulant expansion. The effective mean-field equation with reasonable physical annotation, which is obtained from the lower bound extreme value condition of free energy, can be applied to general statistic mechanics and Lagrangian quantum theory. By applying it to lattices, our theory, for various models containing nonuniform system and nonequilibrium phenomenon, can give a realistic scheme to study the nonperturbative effect order by order. As a testing example to two-dimensional Ising model, we obtain a result approaching the Onsager solution order by order.
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  The Vlasov Equilibrium in the Electrostatically Plugged Tandem Mirror Machine MM-4U

  Xiao-Bing ZHOU, Xi-Wen DENG, Chang-Lin ZHAO, Lin-Zhou MING, Zhong-Yu TIAN

  理论物理通讯. 1995, 24(2): 239-246.

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  The Vlasov equilibrium in the electrostatically plugged tandem mirror machine with double cusps MM-4U is discussed. The plasma potential, density, and non-neutrality profiles are obtained by solving the Poisson-Maxwell equations on the basis of a solution of the Vlasov equation in equilibrium. The truncation conditions of the energy of plasma particles are included. The results show that the potential reaches a maximum and the density gets a minimum at the throat of the machine, i.e., at z = ± 0.36 m. This consorts with the experimental measurements. The non-neutrality profiles show that there are four ion wells in the machine, two at the throats and another two at the centers of cusp.
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  MCHF+BP Approaches of Hyperfine Interaction Constants in ⁴⁵SII

  Guo-Xin CHEN, Shi-Chang LI

  理论物理通讯. 1995, 24(2): 247-250.

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  Multi-configuration Hartree-Fock and configuration interaction calculations of hyperfine structure constants for 3d^{2 3}P states of ScII are reported. It is very important to consider core polarization (especially spin polarization) and core-core correlation as well as valence correlation for accurate calculation of hyperfine constants. The relativistic correction (through Breit-Pauli approximation) as well as finite-nuclear-mass and fnite-nuclear-size-corrected values of the hyperfine constants for ScII are in good agreement with the most accurate experimental values and better than other ab initio theoretical results.
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  On the Transverse Shift of the Reflection and Refract ion of Electromagnetic Waves on the Interface of Dielectric Media

  Zi-Ping LI, Bi-Chu WU

  理论物理通讯. 1995, 24(2): 251-254.

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  Based on the transformation properties of a constrained system under the conformal group, we show that the transverse shift (TS) exists. Some mistakes in Ref [5] are corrected
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  A Possibility of Space-Time Discreteness

  You-Quan LI

  理论物理通讯. 1995, 24(2): 255-256.

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  A possibility of existing minimum time interval is questioned owing to the uncertainty principle. Quantum mechanics on a discrete space (one dimension) and time is discussed. It is shown that the possibility of space-time discreteness provides a new understanding of confinement phenomena.