1991年, 第15卷, 第2期　
刊出日期：1991-03-15

  

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  Slaving Function and Its Convergence

  CAO Li, XU Hai-bo, WU Da-jin

  理论物理通讯. 1991, 15(2): 129-140.

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  Recently, Hong FU, H: Haken and A. Wunderlin proved the convergence of the slaving principle in a simplified model: the Haken model (HM)^[1]. In the present study, by virtue of introducing an auxiliary series of positive terms corresponding to the formal slaving series of variable terms and solving the nonlinear differential equation for the zero order faat variable so(t), we succeeded in generalizing the Hong FU's method to several typical models.
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  Thermal Conductivity of Periodic Composite Media with Spherical Inclusions

  GU Guo-qing, LIU Zen-rong

  理论物理通讯. 1991, 15(2): 141-148.

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  The thermal conductivity of periodic composite media with spherical inclusions embedded in a homogeneous matrix is discussed. Using Green's function, we show that the Rayleigh identity can be generalized to deal with the thermal properties of these systems. A technique for calculating effective thermal conductivities is proposed. Systems with cubic symmetries (including simple cubic, body centered cubic and face centered cubic symmetry) are investigpted in detail, and useful formulae for evaluating effective thermal conductivities are derived.
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  Boson Mean Field Theory of Effective Holon-Holon Interaction in the RVB Model

  Yong-jun LIU, Jin-ming DONG, Chang-de GONG

  理论物理通讯. 1991, 15(2): 149-154.

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  The RVB model is investigated by a mean field theory, in which the holon is expressed by a fermion operator, and the spinon by a boson operator. The effective holon-holon interaction by exchanging the spinons is derived for T≠0. It is found that the interaction is attractive.
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  Superconductivity Window of High T_c Superconductors

  YANG Zhen-qing, KONG Fan-mei

  理论物理通讯. 1991, 15(2): 155-160.

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  The superconductivity window of the Cu-containing high T_c superconductors is studied. It is found that in the case of doping carriers the chemical potential is nonzero and depends on the concentration of carriers δ, which inevitably introduces an upper limit of δ for T_c. The discussion is started with a two-band model Hamiltonian, and the superexchange interactions between 0-0 holes are analyzed by the canonical perturbation theory. Some conclusions are drawn finally.
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  Boundary of Chaos for the Gap Map

  Wei-mou ZHENG, Li-sha LU

  理论物理通讯. 1991, 15(2): 161-168.

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  By means of kneading theory the gap map is studied based on the admissibility conditions.A criterion for the existence of chaos is derived. The structure of the skeleton is analyzed by using two transformations for symbols. The boundary of chaos for the gap map is described.
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  First Principle Calculations of Quasiparticle Energies for Band Structures of Semiconductors

  Jian-qing WANG, Zong-quan GU, Bing-sing WANG, Ming-fu LI

  理论物理通讯. 1991, 15(2): 169-194.

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  We successfully applied the Green function theory in GW approximation to calculate the quasiparticle energies for semiconductors Si and GaAs. Ab initio pseudopotential method was adopted to generate basis wavefunctions and charge densities for calculating dielectric matrix elements and electron self-energies. To evaluate dynamical effects of screened interaction, GPP model was utilized to'extend dieletric matrix elements from static results to finite frequencies. We give a full account of the theoretical background and the technical details for the first principle pseudopotential calculations of quasiparticle energies in semiconductors and insulators. Careful analyses are given for the effective and accurate evaluations of dielectric matrix elements and quasiparticle self-energies by using the symmetry properties of basis wavefunctions and eigenenergies. Good agreements between the calculated excitation energies and fundamental energy gaps and the experimental band structures were achieved.
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  The Thermal Fermi-Gas Model and Liquid-Gas Phase Transitions in Nuclear Matters

  LI Guo-qiang

  理论物理通讯. 1991, 15(2): 195-208.

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  The liquid-gas phase transitions in nuclear matters are investigated by employing the thermal Fermi-gas model and the Skyrme-type nucleon-nucleon interactions. Various situations with different sophistications are under consideration. The nuclear equations of state (EOS), P(p_cT) or µ(p_cT), are derived for these situations. From these EOS, the critical temperature T_c and density p_c are obtained by making use of the inflection conditions.
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  Quantum Electrodynamics at Finite Temperature:One-Loop Corrections to Electron Mass and Magnetic Moment

  SHEN Jun, XU Hong-hua, TSAI Chien-hua

  理论物理通讯. 1991, 15(2): 209-218.

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  Employing the closed-time-path Green's function formalism (CTPGF), the electron selfenergy and vertex function at finite temperature are derived at one-loop level. The so-called "double termn" does not appear in our approach and thus, the unitarity of the theory is ensured automatically. The temperature-dependent mass and vertex corrections are dispersive due to the existence of electron-positron pair background. In the nonrelativistic limit, the explicit forms of shifts due to temperature of both mass and Lande's g factor are given, and their low temperature (T<>m) limits are discussed.
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  Bethe-Salpeter Equation with Self-Energy Graphs I-Generalized Fredholm Theory, Parameter Imbedding Method

  CHENG Geng

  理论物理通讯. 1991, 15(2): 219-228.

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  In this paper the classical Fredholm theory is generalized. The conceptions of the generalized fredholm denominator (GFD) and generalized Fredholm numerator (GFN) are defined. A set of parameter imbedding equations for GFD and GFN is deduced. In this way, the eigenvalue problem of the BS equation in ladder approximation with self-energy graphs, and the eigenvalue problem of nonlinear parameter integral equation, are carried over into an initial-value problem of a set of ordinary differential equations.
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  An Equivalent Reduction of the Bethe-Salpeter Equation for Multi-Fermion Bound States

  Jun-chen SU

  理论物理通讯. 1991, 15(2): 229-250.

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  By means of the renormalized Dirac spinor wave function and through. the introduction of an effective interaction operator, the exact ~ethe-saypetere quation for multi-fermion bound states has been reduced to an equivalent Pauli-Schrodinger equation. As a result, the specific form of the latter equation in the static approximation has directly been given as well. In comparison of the effective interaction operator appearing in the Pauli-Schrodinger equation with the corresponding S-matrix, a substantial difference between both interactions acting in the bound state and the scattering state emerges which is important to determine an interaction potential in the bound state.
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  Pair Approximation Method Applied to a Quantum Transverse Ising Spin-Glass Model

  Yu-qiang MA, Zhen-ya Li

  理论物理通讯. 1991, 15(2): 251-254.

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  The quantum version of the Sherrington-Kirkpatrick model in a transverse field is investigated by combining the pair approximation with the discrete path-integral representation. The free energy and the field-dependent freezing temperature T_c(Г) of the model are obtained,and the classical result for the vanishing of the transverse field (Г → 0) can be reproduced.
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  An Explicit Nonlinear Superposition Formula for the Nonlinear Schriidinger Equation

  Yi XIAO

  理论物理通讯. 1991, 15(2): 255-256.

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  An explicit nonlinear superposition formula for the nonlinear Schrödinger equation is derived for the first time.