Investigation of Dusty Plasma Based on the Ornstein—Zernike Integral Equation for a Multicomponent Fluid

JETP Letters - The electrostatic interaction between charged particles in a dusty plasma has been studied using the Ornstein—Zernike integral equation for a multicomponent plasma. The...     

First-Principles Calculation of Static Equation of State and Elastic Constants for GaSe

The all-electron full potential augmented plane-wave plus local orbital （APW_Io） method with the local-density approximation （LDA） is used to calculate the static equation of state （EOS） and elastic constants of crystalline GaSe. After the full relaxation of atomic positions, the calculated band structure at ambient pressure is consistent with the experimental data to the extent expected to give the known limits of LDA one-electron energies. The equilibrium lattice parameters found here exhibit the usual LDA-induced contraction. However, constrained with the experimental cell volume, the interlayer separation exhibits an expansion due to the LDA underestimate of the weak interlayer bonding. The calculated values of elastic constants are in good agreement with acoustic measurements. The pressure derivatives of the lattice constants derived from the theoretical elastic constants are in very good agreement with x-ray spectra measurements. Two analytical EOSs have been determined at pressures up to 4.5 GPa. The pressure evolution of the structure indicates that the layer thickness decreases slightly under pressure.     

Equation of State of Dense Liquid Nitrogen in the Region of the Dissociative Phase Transition

We have measured the equation of state for liquid nitrogen compressed dynamically to a pressure of 10-60 GPa by employing a two-stage light-gas gun.The data show a continuous phase transition above the shock pressure of 33GPa,as indicated previously by shock wave experiments.A theoretical model has been derived to examine the experimental data by inducing a molecular dissociative fraction.According to theoretical and experimental date the phase transition was thought to be a molecular dissociative phase transition.     

Equation of State of the Fluid He-Ne Binary Mixtures at High Pressures and High Temperatures

The fluid variational free energy model is applied to calculate the equation of state (EOS) of the fluid (Ne/3,2He/3) mixtures at 296K. The pair potential is used to describe the He-Ne interaction. The calculated EOSs at 296Kare compared with the experiments for solid Ne(He)2. The validity of the potential and the calculated model is verified by comparison. The present model is extended to calculate the equation of state of the fluid He-Ne mixtures with different He:Ne compositions in the pressure 0-160 GPa and temperature up to 10000 K.     

Gaseous Metal and the Problem of Vapor–Liquid (Insulator–Metal) Transition in Metal Vapors

Journal of Experimental and Theoretical Physics - We consider the main properties of a gaseous metal, viz., the state of metal vapor adjoining the vapor–fluid transition binodal. The gaseous...     

Calculation of Internal Energy and Pressure of Dense hydrogen Plasma by Direct Path Integral Monte Carlo Approach

The internal energy and pressure of dense hydrogen plasma are calculated by the direct path integral Monte Carlo approach. The Kelbg potential is used as interaction potentials both between electrons and between protons and electrons in the calculation. The complete formulae for internal energy and pressure in dense hydrogen plasma derived [or the simulation are presented. The correctness of the derived formulae are validated by the obtained simulation results. The numerical results are discussed in details.     

Steady State of the Dusty Plasma in a dc Discharge

The steady state formed by the diffusion of plasma particles in an inhomogeneous dusty plasma is investigated theoretically and compared with our previous experimental results [Nucl.Fusion Plasma Phys.20(2000)180 (in Chinese);Phys.Plasmas 8(2001)1459].The negatively charged dust grains with an average charge number of the order of 10^5 on a single grain enhance the plasma inhomogeneity by decreasing the diffusion velocity,and can cause significant depletion of electrons.The theoretical electron density profile is in good agreement with the experiment,and the theoretical profile of the electron-to-ion density ratio is in reasonable agreement with experimentally estimated data.     

Opacity of Hot and Dense Stellar Material： Flexible for Changes in Composition and Abundance

Opacity of stellar materials with the composition and relative abundance specified according to sun has been calculated by using an average-atom scheme, which is designed to treat electronic structures of atoms and ions in a mixture. Different relative abundances of the metallic elements are considered. Oomparisons between the present results and those of OPAL are made for the opacity to show that the difference is less than 10% for mostcases and less than 30% for the largest point with the density of 1.0g/cm^3 and temperatures from 50 to 6000eV. In view of the simplicity of the present approach, it is quite flexible to apply the method to different models of the stellar materials with changes in composition as well as in relative abundance.     

Calculation of the Oscillator Strength for the Klein–Gordon Equation with Tietz Potential

The Klein–Gordon equation under equal scalar and vector potentials is solved for the Tietz potential in D-dimensions by using supersymmetric quantum mechanics. The spectrum of the system is numerically calculated and the oscillator strength is determined and discussed in terms of parameters of the system.     

On the Calculation of the Special Geometry for a Calabi—Yau Loop Manifold and Two Constructions of the Mirror Manifold

JETP Letters - The Kähler potentials have been calculated on the moduli space of complex structures for two Calabi-Yau manifolds specified as hypersurfaces in weighted projective spaces....     

Analysis of the X（1835） as a Baryonium State with the Bethe-Salpeter Equation

We take the X（1835） as a pseudoscalar baryonium state, and calculate the mass spectrum of the baryon-antibaryon bound states pp, ΣΣ, ΞΞ, and ΛΛ in the framework of the Bethe—Salpeter equation with a phenomenological potential. The numerical results indicate the pp, ΣΣ and ΞΞ bound states may exist, and the X（1835） can be tentatively identified as the pp bound state.     

Application of Fermat’s Principle to Calculation of the Errors of Acoustic Flow-Rate Measurements for a Three-Dimensional Fluid Flow or Gas

Fermat’s variational principle is used for derivation of the formula for the time of propagation of a sonic signal between two set points A and B in a steady three-dimensional flow of a fluid or gas. It is shown that the fluid flow changes the time of signal reception by a value proportional to the flow rate independently of the velocity profile. The time difference in the reception of the signals from point B to point A and vice versa is proportional with a high accuracy to the flow rate. It is shown that the relative error of the formula does not exceed the square of the largest Mach number. This makes it possible to measure the flow rate of a fluid or gas with an arbitrary steady subsonic velocity field.     

Monte Carlo Simulation of Opacities of Hot and Dense Au Plasma in the Unresolved Transition Array Approximation

The opacity,and its Planck and Rosseland mean values,of the hot and dense Au plasma in local thermodynamics equilibrium are studied by the Monte Carlo method based on the unresolved transition array (UTA) approximation.The average ion model and the Saha equation are used to determine the atomic level populations.The result gives a more detailed structure for frequency-dependent opacity than the popularly used super transition array or UTA in the photon energy range of 500eV to 2000eV.The Monte Carlo method can give a result better than that of the UTA,with almost the same computation effort.     

On the Incompressible Fluid Limit and the Vortex Motion Law of the Nonlinear Schrödinger Equation

The nonlinear Schr?dinger equation (NLS) has been a fundamental model for understanding vortex motion in superfluids. The vortex motion law has been formally derived on various physical grounds and has been around for almost half a century. We study the nonlinear Schr?dinger equation in the incompressible fluid limit on a bounded domain with Dirichlet or Neumann boundary condition. The initial condition contains any finite number of degree ± 1 vortices. We prove that the NLS linear momentum weakly converges to a solution of the incompressible Euler equation away from the vortices. If the initial NLS energy is almost minimizing, we show that the vortex motion obeys the classical Kirchhoff law for fluid point vortices. Similar results hold for the entire plane and periodic cases, and a related complex Ginzburg–Landau equation. We treat as well the semi-classical (WKB) limit of NLS in the presence of vortices. In this limit, sound waves propagate through steady vortices. Received: 1 December 1997 / Accepted: 27 June 1998     

Population of the Metastable A3Σu State of Molecular Nitrogen under Conditions of Plasma Chemical Synthesis of Metal Nitrides

Technical Physics - The absolute population of the B3Πg state of molecular nitrogen is calculated from the intensity of electron-vibrational bands of the first positive system. The absolute...     

Comparison of Solutions of the General Nonlinear Amplitude Equation and a Modified Schrӧdinger Equation

We review the dynamics of narrow and broad-band optical pulses in nonlinear dispersive media. A major problem that arises during the development of theoretical models, which describe accurately and correctly the behavior of these pulses, is the limited application of the nonlinear Schr?dinger equation. It describes very well the evolution of nanosecond and picosecond laser pulses. However, when we investigate the propagation of femtosecond and attosecond light pulses, it is necessary to use the more general nonlinear amplitude equation. We show that in this equation two additional terms are included and they have a significant impact on the phase of the pulse. We perform numerical simulations and show the temporal shift of the position of fundamental solitons. This effect depends on the initial duration of the laser pulses. To clarify the influence of the additional terms on the parameters of the optical pulses, we consider the nonlinear amplitude equation, which is a modified nonlinear Schr?dinger equation.     

Symplectic Schemes and the Shooting Method for Eigenvalues of the Schrodinger Equation

The one-dimensional time-independent Schr6dinger equation is transformed into a Hamiltonian canonical equation by means of the Legendre transformation, then the symplectic schemes and a new shooting method extended to the eigenvalues of the Schr6dinger equation. The method is applied to the calculations of one-dimensional harmonic oscillator, an anharmonic oscillator and the hydrogen atom. The numerical results are in good agreement with the exact ones.