2001年, 第36卷, 第6期　
刊出日期：2001-12-15

  

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  Identity for the Exponential-Type Molecule Potentials and the Supersymmetry Shape Invariance

  JIA Chun-Sheng, ZHANG Ying, ZENG Xiang-Lin, SUN Liang-Tian

  理论物理通讯. 2001, 36(6): 641-646.

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  The identity and the supersymmetry shape invariance for a class of exponential-type molecule potentials are studied by introducing a deformed five-parameter exponential-type potential (DFPEP) and via the multi-parameter deformations. It has been shown that the DFPEP is a shape-invariant potential with a translation of parameters. By making use of the shape invariance approach, the exact energy levels are determined for the bound states with zero angular momentum. A class of molecule potentials and their exact energy spectra for the zero angular momentum states are reduced from the DFPEP and a general energy spectrum formula, respectively. The interrelations for some molecule potentials are also discussed.
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  Graded Lie Algebra Generating of Parastatistical Algebraic Relations

  JING Si-Cong, YANG Wei-Min, LI Ping

  理论物理通讯. 2001, 36(6): 647-650.

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  A new kind of graded Lie algebra (We call it Z_2,2 graded Lie algebra) is introduced as a framework for formulating parasupersymmetric theories. By choosing suitable Bose subspace of the Z_2,2 graded Lie algebra and using relevant generalized Jacobi identities, we generate the whole algebraic structure of parastatistics.
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  New Approach for Calculating Wigner Functions of Generalized Two-Mode Squeezed State and Squeezed Number State via Entangled State Representation

  FAN Hong-Yi, CHENG Hai-Ling

  理论物理通讯. 2001, 36(6): 651-656.

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  We construct the generalized squeezed vacuum state by virtue of the entangled state 〈η|[Fan Hongyi and J.R. Klauder, Phys. Rev. A47 (1994) 777] and derive the quantum fluctuation of the two-mode quadrature operators.We then calculate Wigner functions of the two-mode squeezed number states and generalized squeezing vacuum state in literature before.
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  Solitary Wave Solutions for the Coupled Ito System and a Generalized Hirota-Satsuma Coupled KdV System

  ZHANG Yu-Feng, ZHANG Hong-Qing

  理论物理通讯. 2001, 36(6): 657-660.

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  We make use of an extended tanh-function method and symbolic computation to construct four kinds of travelling solitary wave solutions for the coupled Ito system and a generalized Hirota-Satsuma coupled KdV system.
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  Bosonic and Fermionic Entropy of (2+1)-Dimensional Charged Black Hole

  CHEN Ju-Hua, WANG Yong-Jiu, JING Ji-Liang

  理论物理通讯. 2001, 36(6): 661-664.

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  From resolving Klein-Gordon equation and Dirac equation in (2+1)-dimensional charged black hole spacetime and using't Hooft's boundary condition and "quasi-periodic" boundary condition in the thin film brick wall model of black hole, which is introduced by LIU Weng-Biao and ZHAO Zheng, we obtain the bosonic and fermionic entropy of (2+1)-dimensional charged black hole, and find that the bosonic entropy is three times of fermionic entropy.
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  QCD One-Loop Effective Coupling Constant and Quark Mass Given in a Mass-Dependent Renormalization

  SU Jun-Chen, SHAN Lian-You, CAO Ying-Hui

  理论物理通讯. 2001, 36(6): 665-672.

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  The QCD one-loop renormalization is restudied in a mass-dependent subtraction scheme in which the quark mass is not set to vanish and the renormalization point is chosen to be an arbitrary time-like momentum. The correctness of the subtraction is ensured by the Ward identities which are respected in all the processes of subtraction.By considering the mass effect, the effective coupling constant and the effective quark masses derived by solving the renormalization group equations are given in improved expressions which are different from the previous results.
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  Independent Plaquette Trial Action for 4-Dimensional Lattice Gauge Theory

  LIU Jin-Ming

  理论物理通讯. 2001, 36(6): 673-678.

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  Based on the explicit expressions of the plaquette formulations, the independent plaquette trial action for 4-dimensional lattice gauge theory is introduced. As an example, the mean plaquette energy E_P for the SU(2) lattice gauge theory is calculated by using action variational approach with the independent trial action. The results are in good agreement with the Monte Carlo results in the strong coupling and the crossover region, and the curve is smooth in the whole region, which show that 4-dimensional SU(2) theory has only a single, confining phase. The unwanted discontinuity of EP given by the single link trial action, which is used in the earlier variational calculations has been avoided.
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  The Solution Construction of Heterotic Super-Liouville Model

  YANG Zhan-Ying, ZHEN Yi

  理论物理通讯. 2001, 36(6): 679-684.

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  We investigate the heterotic super-Liouville model on the base of the basic Lie super-algebra Osp(1|2).Using the super extension of Leznov-Saveliev analysis and Drinfeld Sokolov linear system, we construct the explicit solution of the heterotic super-Liouville system in component form. We also show that the solutions are local and periodic by calculating the exchange relation of the solution. Finally starting from the action of heterotic super-Liou ville model, we obtain the conserved current and conserved charge which possessed the BR ST properties.
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  The Photoionization of Atomic Hydrogen in an Intense Circularly Polarized Laser Field

  ZHANG Deng, ZHANG Qi-Ren

  理论物理通讯. 2001, 36(6): 685-690.

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  We calculate nonperturbatively the irfluence of a strong circularly polarized laser beam on the hydrogen atom energy levels by making use of the time-independent formalism proposed by one of us. The photoionization cross section of the hydrogen atom irradiated by this laser beam and the angular distribution of photoelectrons are also calculated. From the numerical results we clearly see the intensity dependence of the whole photoionization process,including the intensity dependence of the photoelectron energies.
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  The Homotopic Probability Distribution and the Partition Function for the Entangled System Around a Ribbon Segment Chain

  QIAN Shang-Wu, GU Zhi-Yu

  理论物理通讯. 2001, 36(6): 691-694.

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  Using the Feynman's path integral with topological constraints arising from the presence of one singular line, we find the homotopic probability distribution P_Lⁿ for the winding number n and the partition function P_L of the entangled system around a ribbon segment chain. We find that when the width of the ribbon segment chain 2a increases,the partition function exponentially decreases, whereas the free energy increases an amount, which is proportional to the square of the width. When the width tends to zero we obtain the same results as those of a single chain with one singular point.
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  Two-Mode Wigner Operator in 〈ξ| Representation and 〈τ| Representation

  SONG Tong-Qiang, FAN Hong-Yi

  理论物理通讯. 2001, 36(6): 695-698.

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  We derive the two-mode Wigner operator in the 〈ξ| representation and 〈τ| representation, where |ξ〉 is common eigenvector of the mass-weighted relative coordinate and the mass-combinatorial momentum.and |τ〉 common eigenvector of the mass-weighted relative coordinate and the mass-combinatorial momentum. As an application,we calculate the Wigner function of some two-mode state.
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  Power-Law Behavior in Signal Scattering Process in Vertical Granular Chain with Light Impurities

  XU Ai-Guo

  理论物理通讯. 2001, 36(6): 699-704.

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  We investigate the scattering process of impulse in vertical granular chain with light impurities. When the perturbation is weak, the quantities describing the reflection rate exhibit power-law behavior with the impurity depth. The exponent is nearly independent of vi. When the perturbation is very strong, the vertical chain shows similar behavior to that of the horizontal chain, so the exponent is nearly zero. Our numerical investigation begins from the weak perturbation region and extends to the nonlinear region and found a peak of the exponent. The difficulty in extending the numerical investigation to a stronger perturbation region is analyzed.
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  Superconducting Correlations in Small Metallic Grains

  WANG Jing, JI An-Chun, TIAN Guang-Shan

  理论物理通讯. 2001, 36(6): 705-714.

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  By applying the path-integral formulation and the Feynman theorem, we calculate the off-diagonal superconducting correlation in an ultrasmall metallic grain. Unlike its behavior in the bulk limit, we find that this correlation function is an intensive quantity in this case. Therefore, superconductivity is indeed completely suppressed by quantum fluctuations as the diameter of the grain shrinks to the nanometer scale. This conclusion confirms the previous results by numerical calculations. Furthermore, it also imposes a strong constraint on the delocalizing amplitude of the pair-mixing function, which was recently proposed to characterize superconductivity in the canonical ensemble.
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  The Contribution of the Nearest-Neighborhood Interaction to the Persistent Current in a Mesoscopic Ring Studied by a New Model

  HE Guang-Ping, LI Hua-Zhong, MA Zhong-Shui

  理论物理通讯. 2001, 36(6): 715-722.

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  We propose an effective description of the interaction between the nearest-neighboring particles in a continuum theory. The contributions of the electron-electron interaction to the persistent current in 1D strongly correlating mesoscopic rings with or without impurities are analyzed. It is shown that the nearest-neighborhood int eraction gives significant contributions to the current and correlation functions. The enhance of the theoretical value of current magnitude is observed at finite temperature in the presence of the impurity scattering. The statistical property of the persistent current over random impurity distribution is also discussed. It is found that the exponential law of the persistent current for a non-interacting system will remain in an interacting one, as long as the interactions between nonnearest-neighborhoods are excluded.
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  Theoretical Calculations of Thermal Broadenings and Transition Probabilities of R, R' and B Line-Groups for Ruby

  MA Dong-Ping, LIU Yan-Yun, CHEN Ju-Rong

  理论物理通讯. 2001, 36(6): 723-728.

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  On the basis of the unified calculation of the thermal shifts of R₁ line, R₂ line and ground-state-splitting transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings of R, R'and B line-groups for ruby, by taking into account all the levels and admixtures of wavefunctions within d³ electronic configuration and all the ΓM in electron-phonon interaction,the transition probabilities of direct and Raman processes have theoretically been calculated, The thermal broadenings of R,R' and B line-groups have successfully been interpreted in terms of the direct and Raman processes of acoustic phonons. The theoretically predicted transition probabilities are in good agreement with the experimental ones.
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  ab initio Studies on Molecular Conductor (BEDSe-TTF)₂[Fe(CN)₅NO]

  YAO Kai-Lun, TU Hai-Bo, WANG Wei-Zhong

  理论物理通讯. 2001, 36(6): 729-732.

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  In this paper the ab initio study using pseudopotential plane wave method with the local spin density functional approximation is presented for the molecular conductor (BEDSe-TTF)₂[Fe(CN)₅NO]. The mean electronic density distributions are obtained, and we find that the extended π orbital of the selenium does not affect the properties of material as assumed in other papers and the "side-by-side" type S...S interaction is the primary interaction between donors. From band structure calculations we analyze the influence of the NO groups on the electronic structure and magnetic properties of molecule. It is shown that the itinerant electrons important to electronic properties in these types of hybrids are delocalized electrons contributed by NO groups, instead of by the 3d electrons of Fe. Additionally, we have found that the localized magnetic moment is also contributed by the NO groups in this molecular conductor. From total energy calculations the molecular structure with the lowest energy is found due to the interaction between split spins, and the particular positions of the NO groups are obtained.
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  Magnetization of a Gapped Spin 1/2 Antiferromagnetic Ising Chain near the Critical External Field

  LIU Yi-Chang, CHEN Yu-Guan, LOU Ji-Zhong, QIN Shao-Jin, CHEN Hong

  理论物理通讯. 2001, 36(6): 733-736.

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  We study the magnetization of gapped spin 1/2 XXZ Heisenberg Ising chains and calculate the scattering length among massive spinons. We obtain the magnetization close to the critical external magnetic field. The leading correction term determined by the scattering length among massive spinons is given. Our results are in agreement with exact results and with experimental results. We show that the deviation from the massive free hard core boson picture can be accounted very well by the leading correction term due to the spinon-spinon interaction. We show that the deviation increases along with the increasing of the Ising term.
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  Nonlinear Dynamics in a New Double Chain-Model of DNA

  KONG De-Xing, LOU Sen-Yue, ZENG Jin

  理论物理通讯. 2001, 36(6): 737-742.

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  We investigate the mechanics ofa new double chain-model of DNA. The model consists of two long elastic homogeneous strands (or rods), which represent two polynucleotide chains of the DNA molecule, connected with each other by an elastic membrane (or some linear springs) representing the hydrogen bonds between the base pairs of the two chains. The nonlinear dynamical equations are derived and some solitary wave solutions are discussed. By the way,our model can be regarded as the mechanical model of cubic nonlinear Klein-Gordon equation and φ⁴-field equation.
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  Axisymmetric Waves in Isothermal Accretion Discs with Vertical Self-Gravity

  LIU Xiao-Ci, YANG Lan-Tian, WU Shao-Ping, DING Shi-Xue

  理论物理通讯. 2001, 36(6): 743-748.

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  We extend the research of axisymmetric waves in accretion discs with three-dimensional structure to the case that vertical self-gravity of the discs is included. We derive and analyze the dispersion relation and solve the eigenfunctions numerically. The following results have been reached: vertical self-gravity expands the forbidden region of the wave propagation. As the influence of the vertical self-gravity increases, the group velocities of the waves get smaller and the vertical nodes of the wave shrink to the middle plane of the disc.