The general evolution of the interaction of two radiation fields with an effective two-level atom via the Raman-type transitions is presented. Using the Pegg-Barnett phase theory, the joint phase probability distribution of the two field modes, phase average values and phase fluctuations are studied in detail. Also, the effect of the presence of a field on the phase properties of the other mode is examined.

A new kind of theoretical one-dimensional sandpile model is proposed. In contrast to the models studied previously, the sliding process in this model is assumed to be of stochastic nature. Numerical simulations show that the behavior of this model is apparently closer to the reality of true sandpile than the models considered previously. The universality and sealing of this model is also discussed.

Structural behaviors of silicon and germanium clusters under the recently proposed modified Stillinger-Weber (SW) potential have been studied by molecular dynamics method along with the con-jugate-gradient optimization. Since the SW potentials have been derived from the properties of bulk materials, it gives relatively large discrepancy when the cluster number is small, e.g. n=3 and 4. When n>4, the ground-state structures under the modified SW potential are close to that from the first-principle calculation. The binding energies are also improved under the modified SW potential. These results may be attributed to the relative enhancement of the two-body term over the three-body term in the modified SW potential, which leads to structures with a preferential coordination number 4. Structural behaviors of germanium clusters are similar to those of silicon.

Features of optical pulse transmission in a guiding-centre soliton communication system are discussed. The pulse centre jitter and energy fluctuation due to ASE noise in optical amplifiers of the system and the relationships between these effects and the parameters of the system are analyzed. Capability of the maxi-mum length-bit-rate product is estimated, and the capability of the system is compared with that of the common lumped energy compensated system.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

A new method of calculation of EOS and heat of formation of alloy by a modified TFD model is proposed. For elements, only their specific volumes at zero pressure and temperature are required as basic parameters, and the quantum corrections to the kinetic energy are admitted for a better accuracy in later calculations. Nothing more is demanded to be known a priori. Thus computations and analyses for some binary alloys such as Al-Cu, Al-Ni and Al-Co on their EOS as well as heat of formation have been car-ried out in detail. Results obtained are in good agreement with measurements. The theory also provides an explanation for the Miedema's empirical relations between the heat of formation and the eletronic characteristics in alloys. In a subsequent paper it will be shown that there is an intimate correlation between the present theory and the covalent bond theory of Pauling and Yu. It is quite plausible that the TFD model has far wider fields of application and may serve as a probe to both research and design of materials.

By means of the renormalized vertex procedure for the motion Green's function developed by the au-thors, the vertex function of magnetic alloys, based on the s-d exchange interaction, is solved exactly and the corresponding Hall conductivity tensors are obtained. It is found that the renormalized modification of the conductivity is very important in the cases of not too weak extermal magnetic field and slow relexaction time.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

With the help of the decimation ansatz of the renormlization group, the dependence of critical temperature on a transverse magnetic field is calculated analytically for a quasi-one-dimensional disordered superconductor model, based on the de Gennes-Skal-Shklovskii (dGSS) picture of the large cluster in a percolation system. Our results are in good agreement with those given by Halley's scaling theory.

8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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