1998年, 第29卷, 第4期　
刊出日期：1998-06-15

  

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  Complete Ligand-Field Calculation of Energy Spectrum and g Factor of MgO:Ni²⁺ and Their Pressure Effects

  MA Dongping, MA Ning, MA Xiaodong, ZHANG Hongmei

  理论物理通讯. 1998, 29(4): 481-486.

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  The unified calculation of the whole energy spectrum and g factor of ground state for MgO:Ni²⁺ at normal pressure and their pressure-induced shifts has been carried out on the basis of the theory of pressure-induced shifts and the diagonalization of the complete d⁸ energy matrix in a regular octahedral field. A11 the calculated results are in excellent agreement with a lot of experimental data. For the first time, by using the wavefunctions obtained by diagonalization of the complete energy matrix, the pressure-induced shift-of g factor has satisfactorily been calculated and explained by microscopic theory The contributions to typical levels from various parameters have been calculated. The distinct differences of pressure-induced shifts of various levels are immediately determined by their characteristic dependencies on the parameters of interactions. The pressure-induced shifts of levels have provided important criteria for the correctness of the calcutation and assignment of them.
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  Three-Mode Squeezing Operators

  FAN Hongyi, YU Shenxi

  理论物理通讯. 1998, 29(4): 487-490.

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  We search for squeezing operator which squeezes the two quadratures for three-mode optical field as the behavior of single-mode case. The normally ordered form of the squeezing operator is also obtained by virtue of the technique of integration uMin an ordered product of operators.
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  Primary Classification of Quadruply Excited Intrashell States of Atoms

  BAO Chengguang

  理论物理通讯. 1998, 29(4): 491-496.

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  A set of equations are deduced from a consideration of symmetry to pick out states with specific geometric structure. Then the quadruply excited intrashell states are classified according to their geometric feature.
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  A Study of the Characteristics of the Wave Packets of a Paul-Trapped Ion

  FENG Mang, WU Juhao, WANG Kelin

  理论物理通讯. 1998, 29(4): 497-502.

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  Based on the former studies, the time-dependent characteristics of the wave packets of a Paul-trapped ion are investigated explicitly in cylindrical coordinates by the method of function series expansion (HE). It is shown that the present work relates the quantum motion of a Paul-trapped ion to the orbit of the classical motion and presents a more clear physical picture than the former studies.
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  Squeezing Properties of Three-Level Atomic Collective Dipole Phase Quadrature Operators with Respect to Three-Level Atomic Coherent State

  LIU Yuxi

  理论物理通讯. 1998, 29(4): 503-510.

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  We add some useful formulations except for Ref. [4], then investigate the squeezing properties of the atomic collective dipole phase quadrature operators with respect to three-level atomic coherent state in detail. We mainly discuss two extreme cases concerning parameter α and β and obtain some interesting conclusions.
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  Excitonic Effect on the Electron Tunneling Through a Quant urn Well

  DU Yuantai, ZHOU Hong, LIN Tsunghan

  理论物理通讯. 1998, 29(4): 511-514.

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  We proposed a simplified model to describe the excitonic effect on electron tunneling through a quantum well (QW). Using nonequilibrium-Green-function method self consistently, we calculated the dc current of electron tunneling through QW. The extra plateau in the J-V characteristics appears dearly, which shows the existence of exciton in QW. This result is in good agreement with the experiment qualitatively. We also studied the density of electrons and holes in the quantum well.
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  Microscopic Three-Dimensional Theory of Space-Charge-Wave Modes in GaAs-Based Planar Superlattices

  X.L. LEI, N. J.M. Horing, H.L. CUI

  理论物理通讯. 1998, 29(4): 515-522.

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  We report a systematic, fully three-dimensional thkoreticd examination of convective space-charge wave modes of a planar superlattice subject to negative differential miniband conductance (NDC) in a dc bias electric field. Our analysis is based on a set of hydrodynamic balance equations for system having an arbitrary energy band, with an accurate microscopic treatment of phonon and impurity scatterings. When applied to the longitudinal transport of an unconfined planar superlattice, these equations, which take full account of the role of carrier transverse motion, give rise to bulk NDC in the dc steady state conduction and provide a unified formulation to analyze the small-signal ac response in the space homogeneous case and the drift-relaxational modes under spatidy inhomogeneous condition.
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  Homotopy Continuation Approach to Electrostatic Boundary-Value Problems of Nonlinear Media

  GU Guoqing, YU Kinwah

  理论物理通讯. 1998, 29(4): 523-530.

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  The homotopy continuation method is employed to solve electrostatic boundaryvalue problems of nonlinear media. The difficulty associated with matching the inherently nonlinear boundary conditions on the interface is overcome by the mode expansion method, by which the nonlinear partial differential equations of the original problem are transformed into an infinite set of nonlinear ordinary differential equations. In this regard, the homotopy method has to be modified to handle the nonlinear boundary conditions. As an illustration, we study two cases:(a) nonlinear inclusion in linear host and (b) linear inclusion-in nonlinear host, both in two dimensions. The homotopy method is validated by comparing the results with the exact solution of case (a) and the results derived by perturbation method in case (b).
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  Feature of Energy Spectra of Four-Identical-Particle Systems in 2D Space

  XIE Wenfang, RUAN Wenying

  理论物理通讯. 1998, 29(4): 531-534.

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  A comparison has been made between features of low-lying states of a four-electron dot and a 2-dimensional four-alpha-particle system. A series of qualitative features are revealed to be identical. We stress the importance of quantum mechanical symmetries in the understanding of quantum mechanical few-body systems.
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  Quasiclassical Describing of the Bloch Oscillation in a Superlattice by Fokker-Planck Equation

  TIAN Qiang, MA Benkun

  理论物理通讯. 1998, 29(4): 535-538.

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  A theoretical study of Bloch electron transport in a superlattice miniband driven by an electric field parallel to the growth axis is carried out, by Fokker-Planck equation (FPE) in momentum space with the averaged momentum relaxation time (γ) approximation. Steadystate drift-velocity/field characteristics exhibit the expected maximum followed by negative differential conductivity (NDC), and then followed by drift-velocity oscillation when γ or electric field is large. The oscillation frequency is an increasing function of γ, and when γ → ∞, the limit of the oscillation frequency is the Bloch frequency as expected.
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  The Photon-Number Distribution of the Lasers with Binomial Pump Model

  YANG Ming, CAO Li, WU Dajin, LI Zaiguang

  理论物理通讯. 1998, 29(4): 539-542.

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  A method on how to take into account pump statistics and spontaneous atomic decays when calculating the photon-number distribution of lasers in photon-number representation is presented. The intracavity phonon-number and extracavity photocount distributions with binomial pump and spontaneous atomic decays are calculated. In two limit cases, the results of calculations transit respectively to the photon-number distributions of systems with common Poissonian pump and regular pump, and both with the spontaneous atomic decays being suppressed.
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  Robust and Secure Method for Transmitting Binary Message Using Binary Chaotic Sequence

  ZHOU Changsong, CHEN Tianlun

  理论物理通讯. 1998, 29(4): 543-546.

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  Unlike masked with analog chaotic sequence, digital information is masked with binary chaotic sequence with a method proposed by U. Parfitz and 2. Ergezinger (Phys. Lett. 198A (1994) 146). It is demonstrated by numerical simulations that both security and robustness of this communication method are improved. When considered as digital communication, the method is very robust to transmission errors.
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  Analytic Calculation of Arbitrary Matrix Elements for Boson Exponential Quadratic Operators

  PAN Jianwei, HOU Guang, ZHANG Yongde

  理论物理通讯. 1998, 29(4): 547-552.

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  By means of the transformation relation between the ordinary form of boson exponential quadratic operators (BEQO) and its anti-normal product form, we present an effective method to conveniently calculate arbitrary matrix elements of BEQO. By this method, many important matrix elements can be calculated analytically. As a direct application, we obtain the exact solutions of the density matrix and partition function for general boson quadratic Hamiltonian without any information about the energy level.
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  Exact Soliton Solutions for DNLS Equation by the Method of Riemann Problem with Zeros

  YUE Hong, LU Xiaopeng, HUANG Nianning

  理论物理通讯. 1998, 29(4): 553-558.

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  With the procedure to solve explicitly the equations of the Riemann matrix with poles, multisoliton solutions to the DNLS equation are found formally. A single soliton solution is given explicitly and the asymptotic behaviors of multisoliton solutions are discussed.
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  On Kaon Condensation in Dense Nuclear, Matter

  LI Lei, NING pingzhi, ZENG Yuexin

  理论物理通讯. 1998, 29(4): 559-562.

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  The properties of kaons and antikaons in dense nuclear matter are investigated within the framework of relativistic mean-field theory including delta degrees of freedom. The couplings of kaon-baryon interactions are determined by the chiral models. We find that the effective masses and energies of kaons and antikaons are reduced on account of the delta resonance in the nuclear matter. This mechanism may enhance the possibility of the existence of kaon condensation.
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  A Chiral Breaking Field Theory for Giant Multipole States of Nuclei

  ZHANG Qinglan, QIU Xijun

  理论物理通讯. 1998, 29(4): 563-570.

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  The isoscalar giant monopole and quadrupole states of finite nuclei are studied in a relativistic chiral breaking field theory by making use of local Lorentz-boost and scaling method. The nudear surface effect and the density distribution are treated in the relativistic Thomas-Fermi approximation. The excitation energies of the giant resonances are self consistently calculated. The numerical results for the excitation energies are in agreement with experimental data for all nuclei.
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  The Branching Rules for SU(2N)⊃(SU(N)⊃O(N)⊃O(3))⊗SU(2) and the Highest Weight States for SU(N) and O(N)

  SUN Hongzhou, RUAN Dong

  理论物理通讯. 1998, 29(4): 571-578.

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  Simple analytical recurrent formulae of the branching rules for group chain SU(2N)⊃(SU(N)⊃O(N)⊃O(3))⊗SU(2) are obtained. The highest weight states for the irreducible representations [2^al^b] or {nS} of group SU(N) and for the irreducible representations (2^α1^β) or (υS) of group O(N) are constructed respectively
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  Bosonic Realization for Boundary States in Quantum sine-Gordon Field with Boundary

  HOU Boyu, SHI Kangjie, WANG Yanshen, YANG Wenli

  理论物理通讯. 1998, 29(4): 579-586.

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  Boundary operators and boundary ground states in sine-Gordon model with a fixed boundary condition are studied using bosonization and q-deformed oscillators. We also study the boundary bound state for this case.
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  Relativistic Shifted-l Expansion Technique for Dirac and Klein-Gordon Equations

  Omar Mustafa, Thabit Barakat

  理论物理通讯. 1998, 29(4): 587-594.

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  The shifted-l expansion technique (SLET) is extended to solve for Dirac particle trapped in spherically symmetric scalar and/or kvector potentials. A parameter λ = 0, l is introduced in such a way that one can obtain the Klein-Gordon (KG) bound states from Dirac bound states. The 4-vector Coulomb, the scalar linear, and the equally mixed scalar and 4-vector power-law potentials are used in KG and Dirac equations. Exact numerical results are obtained for the Cvector Coulomb potential in both KG and Dirac equations. Highly accurate and fast converging results are obtained for the scalar linear and the equally mixed scalar and 4-vector power-law potentials.
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  Wavefunction and Glueball Masses in QCD:the Three-Dimensional Case

  LUO Xiangqian, CHEN Qizhou, CAI Pengfei, GUO Shuohong

  理论物理通讯. 1998, 29(4): 595-600.

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  We try to develop a possibly more efficient way for extracting the wavefunction and spectroscopy of pure QCD from discretized Hamiltonian field theory. By further exploring the eigenvalue equation method for solving the Schrödinger equation, we find that within thb approach a more suitable choice of the glueball operators can lead to significantly much better results, therefore more rapid convergence to the continuum limit. This is nicely demonstrated in the three-dimensional example.
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  On the Nuclear Effects of Valence Quark Distributions and Sea Quark Distributions

  HE zhenmin, HOU Zhao, DUAN Chungui, YAO Xiaoxia

  理论物理通讯. 1998, 29(4): 601-604.

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  In this paper we present a method which may be used to get the nuclear effect functions R_υ^A(x_t) and R_s^A(x_t) for valence quark distributions and sea quark distributions in the light of the data of 1-A deep inelastic scattering and nuclear Drell-Yan process. Both the functions may be used to test the theoretical models explaining the nuclear effects. With nuclei Fe, Ca and C as examples, the results are shown.
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  Calculation of the Electromagnetic Form Factor of the Kaon

  WAN Shaolong, WANG Kelin, WANG Yi, CHEN Qinghu

  理论物理通讯. 1998, 29(4): 605-608.

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  The wavefunctions of the bound state of the charged kaon are obtained from the Bethe-Salpeter equation with the phenomenological vector-vector-type Aat-bottom potential. The physical space-like electromagnetic form factor of the charged kaon is calculated. The results calculated give a good fit to the experimental values.
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  Chiral Extension of Standard Model and R_c, R_b Problems

  LIU Yaoyang, SUN Lazhen, ZHANG Ziping, JIANG Xiangdong

  理论物理通讯. 1998, 29(4): 609-614.

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  The deviations of R_c, R_b fiom the standard model are discussed within our theory, the cbiral extension of standard model and its supersymmetrization. Combining R_c, R_b with the coupling constants gv, gA of Z⁰ decay, Γ(W⁺ → e⁺υ_e) of W⁺ and the Michel parameters p_γ of γ decay, the mixing angles between hadronic and leptonic quarks and the form factors of the leptonic axial currents are determined within experimental errors, from which it is found that the mass of down leptonic quark of the third generation is about twice the mass of top quark.
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  The Interaction Between Hydrodynamic Nonpropagating Solitons

  WANG Junyi, WANG Wei, WEI Rongjue, WANG Benren

  理论物理通讯. 1998, 29(4): 615-622.

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  The interaction between hydrodynamic nonpropagating solitons in a water tank has been investigated within the framework of Larraza & Putterman and Miles theory. It is shown that these solitons, similar to one-dimensional boats, never pass through each other and exchange places, and thus their interaction can be described in terms of two-body potential. The interaction potential for two solitons with opposite polarity and that for solitons with like polarity are found to be pure repulsive and anharmonic, respectively. Based on the results, it is explained well why two solitons of an opposite pair repel each other as a distance is reached. while that of a like pair can oscillate about each other.
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  Lattice Boltzmann Simulation of van der Waals Phase Transition with Chemical Potential

  HE Gang, ZHAO Kaihua

  理论物理通讯. 1998, 29(4): 623-626.

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  In this paper phase transition of van der Waals gas is simulated by the Boltzmann lattice method. Thermodynamics and chemical potentials have been taken into account.
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  Motion of Solitons in Deoxyribonucleic Acid (DNA) Double Helices with Dissipation

  HA1 Wenhua, HE Chuguang, ZHANG Li, LI Siping

  理论物理通讯. 1998, 29(4): 627-632.

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  Under the first-order approximation, the general soliton solution of the plane base rotator model is obtained using the direct perturbation method, when taking the dissipation interaction in the DNA double helices dynamics into consideration. The stability condition of system leads to a relation among the soliton velocity, the coupling constants and the damping factor. It imposes limits to the maximum value of the soliton velocity and energy. An estimation of the value of the dissipation factor is given using recently published experimental data. Some practical problems such as the energy transmission and the semiconservative replication of B-DNA are discussed in detail.
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  Properties of the States Generated by the Excitations on a q-Coherent State

  XU Jingbo, CAI Shoufu, GAO Mu, WANG Qinmei

  理论物理通讯. 1998, 29(4): 633-636.

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  We study the mathematical and physical properties of the states which are generated by excitation on a q-analogue of the coherent state. With the help of a q-analogue of the Laguerre polynomial, the squeezing and the statistical properties of the field in such the state are also discussed.
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  Nonlinear Evolution Related to Invariant Functionals and the SUSY Transformations

  ZHOU Zhuomei, CAI Xu

  理论物理通讯. 1998, 29(4): 637-640.

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  A supersymmetrized formalism of the nonlinear evolution equations and the relation to the invariant functional are discussed.