1992年, 第17卷, 第4期　
刊出日期：1992-06-15

  

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  The Theoretical Calculation of Elastic Constants and Phonon Dispersion Curves of Ca_0.86Sr_0.14CuO₂

  Yao-Ming MU, Rui-Bao TAO

  理论物理通讯. 1992, 17(4): 385-388.

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  The lattice dynamical properties of Ca_0.86Sr_0.14CuO₂ are studied with a shell model. Its elastic constants and phonon dispersion curves are predicted. The calculated optical mode frequencies in Γ point are in reasonable agreement with infrared spectra, except an Azu symmetry mode around 180 cm^-1. Our calculated results can serve as guide for further experimental investigation.
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  Isothermal Compression Behaviors of 6 Polymers up to 2 Kbar

  Zu-Tong YAN

  理论物理通讯. 1992, 17(4): 389-392.

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  The applicabilities of universal equation of state and Birch-Murnaghan equation of state to isothermal compressions of 6 polymers in the liquid, glassy and crystalline states have been examined up to 2 Kbar at various temperatures. The results show that the universal equation of state is very accurate for fitting the isothermal P - V data of polymers in the liquid, glassy and crystalline states, and that the information of the pressure-induced transition is obtained, and that the Birch-Murnaghan equation can also be used but it is not as good as the universal equation of state.
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  Chaotic Phenomena in a Two-Photon Laser with Injected Signal

  Ying-Hai WANG, Yu-Ping GUAN

  理论物理通讯. 1992, 17(4): 393-400.

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  The instability and the chaotic phenomena in a two-photon laser with injected signal are discussed for the homogeneously broadened single mode ring cavity. The structure of the system's attractors is considered by using the Lyapunov exponents and the Lyapunov dimension. The strange attractors of chaos and superchaos are found. The strange attractor displaying superchaos is not observed in one-photon laser with injected signal.
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  Study of Heisenberg Antiferromagnetic Superlattices

  Shi-Min CUI

  理论物理通讯. 1992, 17(4): 401-408.

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  A Heisenberg antiferromagnetic superlattice is studied by using the Green's function technique. The relations which determine the layer magnetization, the spin-wave spectrum and the N6el temperature etc. are obtained. The interlayer coupling dependence of the layer magnetization at low temperature is discussed for simple cases.
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  The Systematic Approximation and the Systematic Adiabatic Approximation for the Stochastic Systems Driven by O-U Noises

  Jing-Hui LI, Li CAO, Da-Jin WU

  理论物理通讯. 1992, 17(4): 409-420.

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  In this paper, we generalize the systematic approximation and the systematic adiabatic approximation developed by G. Schöner and H.aken^[1,2] to the stochastic systems driven by O-U noises. After eliminating the fast variables st, we introduce a new family of stochastic processes K_t^(υ) (υ≥2) in the equations for the order parameters vt. A typical model serves to illustrate how to derive the equation for the order parameter and how to calculate the statistical properties of the new stochastic processes K_t^(υ) (υ≥2). Some significant discussions and conclusions are given in Sec. V.
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  The Average Free Energy and the Effective Mean Field Hypothesis

  Yong-Xin SONG, Shao-Kang ZHOU

  理论物理通讯. 1992, 17(4): 421-424.

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  In this paper, an improvement in the variational-cumulant expansion method is made. For any model in lattice field theories, the average free energy can be calculated rigorously according to the generalized cumulant expansion, and the intensity of the effective external field can be determined by the effective mean field hypothesis. As a test, the king model is studied, and the results take a visible turn for the better.
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  Critical Point of the Honeycomb Antiferromagnetic Ising Model in a Nonzero Magnetic Field: An Analytical Analysis

  Y.X. SONG, J.M. YANG, G.R. LU

  理论物理通讯. 1992, 17(4): 425-428.

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  In this paper we determined the critical point of the antiferromagnetic Ising model in a nonzero magnetic field on the honeycomb lattice by an analytical method-the generalized cumulant expansion with the mean field hypothesis. By calculating the magnetization to the fourth order correction, we get encouraging results when compared with the known numerical results by finite size analysis.
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  The Quantum R-Matrix via Canonical Quantization in the Liouville Theory

  Hong-Bing FEI, Han-Ying GUO, Zhong-Hua WANG

  理论物理通讯. 1992, 17(4): 429-438.

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  Starting from the classical Liouville theory, we study its quantum theory through canonical quantization. We find that if the Poisson bracket relations between two vectors are,dominated by the classical r-matrix in the classical case, their quantum analogue is replaced by the exchange relations dominated by the quantum R-matrix. The quantum group structure in the quantum LiouviUe theory is studied and the central charge of the quantum Liouville theory is also obtained.
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  Spinor and Oscillator Representations of Quantum Enveloping Algebras of Type B_n, C_n and D_n

  Li LIAO, Xing-Chang SONG

  理论物理通讯. 1992, 17(4): 439-448.

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  With the help of the q-deformed bosonic and fermionic oscillation operators, which can be conetructed from the ordinary ones, the quantum enveloping algebras of the classical Lie algebras B, C and D are written down explicitly. Under these representations the highest roots are given.
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  q-Deformed SU(1,1) ⊗ SO(6) Spectra of Interacting s, d Bosons in Nuclei

  Yu-Cheng WANG, Ze-Sen YANG

  理论物理通讯. 1992, 17(4): 449-454.

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  The quantum groups SU_q(1,1) and SU_q(2) are used to describe the interacting s, d bosons system which hae the q-deformed SU(1,1) ⊗ SO(6) dynamic symmetry and a Hamiltonian similar to that of O(6)-limit in the interacting boson model is constructed. Three regions of q-number are taken to analyze the influences of deformation on the deformed SU(1,1) ⊗ SO(6) spectra. It is found that the deformation parameter has important influences on the higher excited states within a quasi- rotational band. Yt isotopes with O(6) characteristics are investigated.
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  Intermediate Range Force Contributions to Dynamical Chiral Symmetry Breaking in QCD

  Xin-Heng GUO, Tao HUANG

  理论物理通讯. 1992, 17(4): 455-458.

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  We propoee the intermediate range QCD force singular like δ(q) by analysing the gluon propagator in the nonperturbative region from QCD sum rules. With the help of the Slavnov- Taylor-Ward identity we derive the equations for the nonperturbative quark propagator from the Schwinger-Dyson (SD) equation. Solutione for the quark propagator in two special cases are given. We find that the intermediate range force L also responsible for the chiral symmetry breaking in QCD.
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  New Investigations on Meson Spectra Based on the Relativistic Equation for qq Bound States

  Jun-Chen SU, Yu-Bing DONG, Qing-Jun LIU

  理论物理通讯. 1992, 17(4): 459-468.

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  By considering the retardation effect of gluon propagation and a general Lorents structure of the confinement, a retarded and off-shell one-gluon exchange potential and a harmonic oscillator-dominant confining potential with a certain relativistic corrections are derived based on the relativistic Pauli-Schr6dinger equation for quark-an tiquark bound states. Use of these potentiale to caJculate meson spectra leads to the results which are in good agreement with the experimental data.
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  An Approach for Calculating Antinormally Ordered Form of Squeezing Operators

  Hong-Yi FAN

  理论物理通讯. 1992, 17(4): 469-472.

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  In this work we present a new approach for deriving the antinormal product forms of some types of squeesing operators. This approach is based on the technique of integration within antinormally ordered product of opertors which ie previously introduced in Ref.
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  Possible Supernova Multi-Explosions and Induced Gravitational Collapse

  Cheng-Rui CHING, Tso-Hsiu HO, Yi-Ren WANG, Jing YAO

  理论物理通讯. 1992, 17(4): 473-484.

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  In this paper, three hotly discussed problems, namely the neutrino bursts, the blue progenitor, and the mixing phenomenon, observed in SN1987A are summarized. But it is pointed that while all the observations on SN1987A do not favour a twice-banged scenario, we have found three historical cases from ancient Chinese documents that might be interpreted as twice- or even multi-explosions of a supernova. Finally in a one-dimensional simulation we demonstrate that an induced gravitational collapse b possible.
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  Cold-Fluid Analysis of the Space-Charge Effects in an Electromagnetically Pumped Free-Electron Laser with an Axial-Guide Magnetic Field

  San-Kui GOU

  理论物理通讯. 1992, 17(4): 485-486.

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  The space-charge effects are analysed and five kinds of fluid waves are obtained in the e-beam density and the axial-current density for an electromagnetically pumped free-electron laser with an axial-guide magnetic field by using the cold-fluid theory. To enhance the gain, the guide field Bo must be in this regime: -2(ω_υ + cβ_x0k_ω) < Ω < -(ω_υ + cβ_x0k_ω), where Ω₀ = eB₀/mr₀ and ω_υ(k_ω) is the frequency (wave number) of the wiggler.
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  Dual Coupling in the Soliton Pairing Model of Superconductivity

  Yong-Li MA, Xian-Xi DAI

  理论物理通讯. 1992, 17(4): 487-490.

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  A ø - ø superconducting field theory for the soliton pairing mechanism ie studied. Using the variational method the dynamics of fields shows that the mechanism is understood in terms of the dual coupling: vortex field and string field. Important experimental implications are discussed.
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  The Effect of e-e Interaction on Polaron in N-Type Semiconductor of Polyacetylene

  Yun-Long CUI, Sen-Hao LIN, Jia-Hua ZHANG

  理论物理通讯. 1992, 17(4): 491-494.

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  The effect of e-e interaction considered with the familiar Hubbard model on the polaron in N-type semiconductor of trans-polyacetylene has been studied. When the parameter of e-e repulsion varied from 0 to 4 eV, we found that the conduction and the valence band structure were altered slightly, but the density of the chain and the polaron levels were modified severely.
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  Stochastic Resonance in Nonequilibrium Single-Stable System

  Jing-Dong BAO, Yi-Zhong ZHUO, Xi-Zhen WU

  理论物理通讯. 1992, 17(4): 495-498.

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  The harmonic noise is used as an external stochastic source in non-Markovian equilibrium system. A bi-peak resonance phenomenon is carried out due to the external nohe frequency close to the frequencies of damped linear-oscillatpr and internal noise, respectively.
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  θ Statistics and Quantum Group

  Yi-Xin CHEN, Guang-Jiong NI

  理论物理通讯. 1992, 17(4): 499-504.

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  General theory of quantum statistics with internal degree of freedom in two dimensions is studied. Because of the topological nontrivial properties in the configuration space of indistinguishable particles, the intrinsic part of many-body wave function is associated with the representation of quantum group, which describes θ statistics. The statistical potential and the effective Hamiltonian of general two-dimensional system can be derived from the Kohno connection.
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  A Fibre-Bundle Treatment to a Class of Extended Gauge Models

  C.M. Doria, R.M. Doria, J.A. Helayël-Neto

  理论物理通讯. 1992, 17(4): 505-508.

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  We adopt the analytic approach to connections on a general vector bundle to discuss the independence of vector gauge potentiah introduced simultaneously in association with a single simple group.
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  A Possible Origin of e⁺e^- Peaks in Heavy-Ion Collisions

  Zhen-Fei LUO, Xi-Jun QIU

  理论物理通讯. 1992, 17(4): 509-512.

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  The behavior of a neutral composite particle composed of a positron and an electron in the strong Coulomb field of a nuclear uquasimolecule formed in low-energy heavy-ion collions is examined. A strong attractive interaction between the composite particle and the Coulomb field is found when the combined nuclear charge of two nuclei is sufficiently large, which is possible to lead to the e⁺e^- pair production in heavy-ion collisions.