1990年, 第14卷, 第1期　
刊出日期：1990-07-30

  

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  Optical Properties of Metal-Insulator Fibonacci Quasi-Periodic Superlattice

  Nian-hua LIU, Wei-guo FENG, Xiang WU

  理论物理通讯. 1990, 14(1): 1-8.

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  Based on the hydrodynamic theory and the transfer-matrix method, we have studied the optical properties by taking account of damping effects to the system of the metallic. and dielectric Fibonacci quasi-periodic superlattice for s-polarized soft x-rays and extreme ultraviolet. The analytical expression for the reflectivity is formally given. From our numerical results, we find that besides the reflection intensity spectrum has a very rich structure of self-similarity, the stronger reflection peaks appear at the region of soft x-rays and ultraviolet compared with metal-metal superlattice, and the width of the maxima is dependent on the dielectric functions of metallic and dielectric media. By using the periodic condition approximation, we also distussed the electromagnetic normal modes in the system, which explains the reflection spectra, and we found that with the increasing of the generation number, the electromagnetic modes all become localized.
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  Intermediate Coupling Electron-Phonon Interaction in a Quantum Well

  Jing-qi MIA0, Shi-wei GU, Qian-li YANG

  理论物理通讯. 1990, 14(1): 9-20.

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  An intermediate-coupling exciton-phonon system allowing for the Gabovish image potential in a quantum well is considered for the first time. The detailed study on the motional property of the exciton in the z direction shows that the thinner the well, the more accurate the square well approximation and some new properties on the exciton are found.
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  Elimination of Fast Variables for a Class of Nonlinear Stochaqtic Dynamical Systems

  CAO Li, WU Da-jin

  理论物理通讯. 1990, 14(1): 21-34.

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  A set of nonlinear stochastic differential equations (NSDE's) that describes a large class of nonlinear stochastic dynamical systems is studied. By virtue of the stochastic generalization of. usual adiabatic approximation, we obtain the solution of equation for the fast variable, and obtain a closed equation for the slow variable. The statistical properties of the-new stochastic variables occurred are studied. The formal NSDE's are treated in the Stratonovich sense and the Ito sense respectively.
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  Lie Algebraic Solution of Nonlinear Fokker-Planck Equation

  JIANG Lu

  理论物理通讯. 1990, 14(1): 35-40.

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  The algebraic structure for nonlinear Fokker-Planck equation is discussed. By using Lie algebraic techniques, the exponent operator equation can be decomposed. A time evolution solution of nonlinear Brownian motion is given and can be compared with other theories.
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  The Angular Distribution of Light Particle Projectile Based on a Semi-Classical Model

  ZHANG Jing-shang

  理论物理通讯. 1990, 14(1): 41-52.

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  A semi-classical model of multi-step direct and compound nuclear reactions is proposed to describe the angular distributions of the light particle projectiles from reaction processes induced by a nucleon with energies of several tens of MeV. The exact closed solution to the time-dependent master equation of the exciton model is applied. Based on the Fermi gas model, the scattering kernal between two-nucleon collieion includes the influences of the Fermi motion and the Pauli exclusion principle, which give the significant improvement to rise of the backward distributions. The energyangular correlation for the first few steps of the collision process (muli-step direct process) yields the further improvement of the angular distribution. The pick-up mechanism is employed to describe the composite particle emission. Thh reasonable physical picture reproduces the experimental data of the energy spectra of the composite particles satisfactorily. The angular distribution of the emitted composite particle is determined by an angular factor in terms of the momentum conservation of the nucleons forming the composite cluster. The generalized master equation is employed for the multi-step compound process. Thus a classical approach has been establised to calculate the double differential cross sections for all kinds of particles emitted in multi-step nucler reaction processes.
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  Semiclassical Approach for Static and Dynamical Properties of Nuclei

  LI Guo-qiang

  理论物理通讯. 1990, 14(1): 53-98.

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  This article summarizes recent progress in the semiclassical treatment of nuclear static and dynamical problems. We first give a short outline of fundamental concepts adopted in the semiclassical approximations, including h-expansion, Bloch density matrix and Wigner-Kirkwood transformation. Then we proceed to discuss two major types of semiclassical approaches:self-consistent semiclassical calculation and its extended forms for deformed and hot nuclei for static properties of nuclei, and Vlasov equation, including its extension Vlasov-Uehling-Uhlenbeck equation, for dynamical properties, especially the collisional problems, of nuclei.
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  Beltrami Gauge Symmetry and 2D Induced Gravity

  Han-ying GU0, Shi-kun WANG, Zhong-hua WANG, Ke WU

  理论物理通讯. 1990, 14(1): 99-106.

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  We introduce the Beltrami gauge symmetry related to the Beltrami parametrization of the metrics and the Beltrami equations. We explore its role in 2d induced gravity and show that Polynkov's. SL(R) and KPZ's residual symmetries are subsymmetries of the Beltrami gnuge symmetry in the light-cone gauge. We also find that the 2d induced gravity with or without matter can be reformulated as Beltrami-Liouville field theories on Riemann surfaces of higher genus.
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  The Scaling Exponent for 2-Dimensional 6-State Potts Model

  CHEN Tian-lun, HUANG Wu-qun

  理论物理通讯. 1990, 14(1): 107-110.

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  Using an optimal Monte Carlo renormalization group method, the scaling exponent for six-state Potts model on 2-dimensional random triangle lattice ie studied. The scaling exponent υ=0.54, is consistent with the expectant value of the scaling theory.
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  Second Order Phase Transitions in Z(2) Gauge Theory by Variational Cumulant Expansion

  Jin-min YANG

  理论物理通讯. 1990, 14(1): 111-116.

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  The four-dimensional Z(2) gauge theory with asymmetric couplings is studied by variational cumulant expansion. An interesting phase structure with a second order transition line is given. The comparison with the result of Monte Carlo simulation is also presented.
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  Stochastic Quantization and Anomaly Associated with Axial-Vector Field

  ZHOU Jian-ge, DAI Qing-hai, LIU Yiao-yang

  理论物理通讯. 1990, 14(1): 117-122.

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  The method of stochastic quantization of Fermi field is used to calculate the anomaly associated with axial-vector field in arbitrary even dimensions. The result obtained is the gauge-covariant anomaly.
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  Beltrami Algebra and Its Operator Formalism

  Han-ying GU0, Jian-min SHEN, Shi-kun WANG, Kai-wen XU

  理论物理通讯. 1990, 14(1): 123-128.

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  We construct the Beltrami algebra related to quaaiconformal transformation on torus and its BRST formalism. The formalism shows the central charge of the Beltrami algebra is equal to 28, that is c=28.