Approxiamation theory for unequal amplitude soliton pairs in nonliear optical fibers

The equivalent-particle approach is used to investigate the interaction of two unequal-amplitude solitons propagating in nonlinear fibers by regarding the interaction as a perturbation. The Newtonian equations for the motion of solitons are given. Results show that the interaction of an unequal-amplitude soliton pair can be approximated as the product of a local interaction factor dependent on the propagation distance and a nonlocal interaction factor independent of the propagation distance. The local factor forces soliton interaction to alternate between the attractive and the repulsive, and, on a large scale, the average of this character markedly reduces the interaction of the unequal-amplitude solitons.     

Kondo quantum dots and the novel Kondo-doublet interaction

We analyze the interactions between two Kondo quantum dots connected to a Rashba-active quantum wire. We find that the Kondo-doublet interaction, at an interdot distance of the order of the wire Fermi length, is over an order of magnitude greater than the RKKY interaction. The effects induced on the Kondo-doublet interaction by the wire spin-orbit coupling can be used to control the quantum dots spin-spin correlation. These results imply that the widely used assumption that the RKKY is the dominant interaction between Anderson impurities must be revised.     

Relations between lattice dynamics of simple metals and liquid state properties

The actual interaction between ions in a metal is divided into the direct interaction of the ion cores and the ion-electron-ion interaction. The ion-electron-ion interaction is treated according to the Hartree-Fock approximation modified by a screened exchange potential. Since until now the bare ion potential is not known very accurately, the observed phonon frequencies were used to determine a model pseudopotential with the least squares method. Using this model pseudopotential the electronic band structure, the density of states as well as the electrical resistivity of molten Na, K, Al and Pb were calculated.     

Lattice dynamics,electronic structure and electrical properties of simple metals

The actual interaction between ions in a metal is divided into the direct interaction of the ion cores and the ion-electron-ion interaction. The ion-electron-ion interaction is treated mathematically according to the Hartree-Fock approximation modified by a screened exchange potential. Since until now the bare ion potential is not known very accurately, the observed phonon frequencies were used to determine the pseudo-potential with the least squares method. Using this pseudo-potential, some electronic and electrical properties are calculated. Their good agreement with experimental results confirms the general correctness of the model pseudo-potential and screened ion basis for setting up the potential in a simple metal.     

Van der Waals interaction between an atom and a surface defect

A continuum dielectric theory is used to investigate the Van der Waals interaction between an atom and a point defect on a planar surface. A vacancy (or adsorbed atom) is modelled by a hemispherical pit (or bump) which perturbs the dielectric response of the defect-free surface. The anisotropy of the interaction is found to be qualitatively different for the vacancy and adsorbate situations. The estimated magnitude of the interaction seems consistent with recent experimental results.     

Acoustooptic interaction of beams close to forbidden directions

The theory of acoustooptic interaction of beams taking into account the drift and spreading of beams in an anisotropic medium is presented. The problem is solved analytically for a weak interaction of Gaussian beams close to forbidden directions. The possibility of existence of collinear diffraction of wave beams along the direction forbidden for interaction of plane waves is shown theoretically. The interaction appearing close to such a direction was found to result in a certain distortion of the beam shape. The calculation performed for a paratellurite crystal shows that the efficiency of the diffraction along the forbidden direction can reach 10% at the acoustic power usually used.     

Application of a green function to a metal containing a vacancy and an impurity atom

A double time Green function is used to obtain the interaction energy between a vacancy and a transition-metal impurity atom in noble metals. The main part of the interaction energy has the RKKY type expression.     

Transport and thermodynamic properties of a 2DEG in the presence of tilted magnetic field: the influence of Dresselhauss interaction

The effect of Dresselhauss spin-orbit coupling on transport and thermodynamic properties of a non-interacting two-dimensional electron gas (2DEG) is investigated. The Hamiltonian used also includes a tilted magnetic field and a Rashba spin-orbit interaction. The Dresselhauss spin-orbit interaction, likewise the Rashba spin-orbit interaction, introduces a beating pattern in the conductivity tensor and in the magnetization along the field direction. A method to estimate the contribution of the Rashba and Dresselhauss interactions to the beating pattern is given using the periodicity of the beating patterns.     

Account of the nonbinary nature of the ion interaction in lattice dynamics

The real multiparticle Hamiltonian for a solid with a Coulomb interaction between electrons and nuclei is used in the approximation of dynamic independence of the electrons from the ionic and valence shells to obtain an expression for the crystal energy in terms of the ion-ion interaction and the pseudopotential for the interaction of a valence electron with an ion. A correction to the dynamic matrix due to the existence of a three-particle interaction among ions is found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 88–94, September, 1970.     

A simple model for short-range correlations in nuclear matter

It is shown that Pauli blocking and short-range correlation effects, which strongly renormalize the bare nucleon-nucleon interaction in the medium, can be summarized in a correlation operator which has an extremely simple structure. The use of such a simple correlation operator leads to a form of Brueckner's reaction-matrix interaction which is very convenient for applications. The effective interaction introduced by the Jülich-Stony Brook group and extensively used in the study of the spin-isospin excitation modes in nuclei is derived from a meson exchange potential.     

钠原子nd高Rydberg系列能级精细结构的计算研究

采用一种新的数值计算方法求解原子体系的相对论Hartree-Fock（RHF）方程.给出了Breit作用中迟滞项的非常清晰、简洁的表示形式.利用建立起来的理论方法和计算程序,计算了Na原子nd（n=17—31）系列能级的精细结构.有别于其他理论计算中多采用微扰论方法,用RHF方法通过自洽迭代直接求解精细结构的能级分裂值,得到了与实验值基本一致的精细结构倒置的计算结果.结果表明相对论架构下原子实电子与价电子的交换作用是导致精细结构反转的主要原因.用微扰方法计算了精细结构分裂中的Breit效应, 关键词： 精细结构 Na原子 相对论Hartree-Fock（RHF）方程 Breit效应     

On the applicability of the average exchange model for electron spin polarization phenomena

The applicability of the average exchange model as a tool for describing electron spin polarization in micelles is investigated by comparison with analytical and numerical results. The analytical results are used for the interpretation of the various types of dependence, while the numerical results are used for quantitative tests. It is demonstrated that the dephasing effect of the exchange interaction has a significant influence both on the time dependence and on the stationary value of the polarization. Dephasing arising from the exchange interaction is not included in the average exchange model, and therefore the spin dynamics are not described correctly. The average exchange model can only be used to estimate the frequency and the stationary value of the polarization, and only in the case of very slow singlet-triplet mixing, weak exchange interaction, and low reactivity of the radicals.     

High-pressure equation of state for solid krypton from interatomic potentials

The pressure-volume isotherm for krypton at 300 K is evaluated by the Monte Carlo method using pair and three-body potentials. The pair potentials used are that of Aziz and Slaman and a slightly modified version of their potential which gives better agreement with high-energy scattering data. The three-body potentials considered are the Axilrod-Teller interaction and the first-order three-body exchange interaction as parametrized by Loubeyre. The results are compared with recent measurements at pressures up to 300 kbar and the implications of the comparison are discussed. The best agreement with experiment is found using the Axilrod-Teller interaction as the only many-body interaction, indicating that the three-body exchange interaction is to a large extent canceled by higher many-body interactions, at least in the highly symmetrical environment of the crystal.This paper is dedicted to Howard Reiss on the occasion of his 66th birthday.     

Effects of vibrational anharmonicity on 19F nuclear resonance in SF6

A Barker-Henderson like perturbation theory for polyatomic fluids is developed. The molecular interaction forces are assumed to be described by an interaction site model potential and the reference system is a fluid of hard interaction site model molecules.

The theory is used to study the equation of state of nitrogen, the theoretical results being compared with experimental data and with those coming from other theories. The agreement between theory and experiment is as good as that shown by Barker and Henderson theory for monoatomic systems.     

THE APPLICATIONS OF NUCLEAR SPIN RELAXATION TO POLYMER DYNAMICS AND INTERMOLECULAR INTERACTIONS

The correlation functions of the side - groups and side ?chains of polymers are obtained for nuclear spin relaxation if the segmental motion of the polymers is described by VJGM model, these functions are derived from unequal two ?side and three -site jump internal rotation, diffusion internal rotation, restricted internal rotation and multiple internal rotation. The corresponding spectral density functions are also given, and these functions are used to interpret the nuclear spin relaxation data of the side-groups of some polymers. The average spectral density functions of side-groups are derived under the magic angle spinning, the correlation times and diffusion coefficients of the side-groups of crosslinked poly (methyl methacry-latcs) and solid poly(vinylbutyral) are obtained by using these average spectral density functions. The multiphase structures of nylon 6, poly (ethylenc glycol) and its complexes are investigated with cross ?polarization and magic angle spinning techniques.Three methods using     

Quantum phase transition between a Luttinger liquid and a gas of cold molecules

We consider cold polar molecules confined in a helical optical lattice similar to those used in holographic microfabrication. An external electric field polarizes molecules along the axis of the helix. The large-distance intermolecular dipolar interaction is attractive but the short-scale interaction is repulsive due to geometric constraints and thus prevents collapse. The interaction strength depends on the electric field. We show that a zero-temperature second-order liquid-gas transition occurs at a critical field. It can be observed under experimentally accessible conditions.     

Quantum nondemolition measurement of photon—number distribution for a weak cavity field with resonant atoms

We propose a quantum nondemolition measurement of the photon-number distribution for a weak cavity field with no more than two photons. The scheme is based on the resonant interaction of atoms with the cavity field, and thus the required interaction time is much shorter than that using dispersive interaction. This is important in view of decoherence. Our scheme can also be used to generate even and odd coherent states for a weak cavity field with resonant atoms.