Debye screening

The existence and exponential clustering of correlation functions for a classical coulomb system at low density or high temperature are proven using methods from constructive quantum field theory, the sine gordon transformation and the Glimm, Jaffe, Spencer expansion about mean field theory. This is a vindication of a belief of long standing among physicists, known as Debye screening. That is, because of special properties of the coulomb potential, the configurations of significant probability are those in which the long range parts ofr ^–1 are mostly cancelled, leaving an effective exponentially decaying potential acting between charge clouds. This paper generalizes a previous paper of one of the authors in which these results were obtained for a special lattice system. The present treatment covers the continuous mechanics situation, with essentially arbitrary short range forces and charge species. Charge symmetry is not assumed.Supported in part by N.S.F. Grant PHY 77-02187 and MCS 79-02490     

Debye screening of dislocations

Debye-like screening by edge dislocations of some externally given stress is studied by means of a variational approach to coarse grained field theory. Explicitly given are the force field and the induced geometrically necessary dislocation (GND) distribution, in the special case of a single glide axis in 2D, for (i) a single edge dislocation and (ii) a dislocation wall. Numerical simulation demonstrates that the correlation in relaxed dislocation configurations is in good agreement with the induced GND in case (i). Furthermore, the result (ii) well predicts the experimentally observed decay length for the GND developing close to grain boundaries.     

Debye screening versus Gauss law in electrostatics: Finite size effects

We revisit the well-known topics of self- and induced-screening in an otherwise isotropic neutral plasma/colloid. It is pointed out that the standard Debye-Hückel (DH) theory (ignoring finite size effects) suffers from many ambiguities related to net ionic numbers, total charge of the system, role of the electrostatic Gauss law, short-distance behaviour of the potential and incorrectly normalized pair correlation functions. We give a new formulation (incorporating finite size effects) such that ionic numbers are maintained, the total charge of the system has physically correct value, the Gauss law boundary conditions are rigorously obeyed, short-distance behaviour of the potential is guaranteed automatically, and correlation functions are correctly normalized. Numerical differences between the two approaches show up if the screening length μ⁻¹ becomes comparable to the size R of the system.     

Surface Debye temperature in desorption kinetics

Desorption times for gas-solid systems with localized or mobile physisorption are calculated with the desorption energy supplied by the surface phonon modes of a semi-infinite elastic solid. They are shorter by a factor 2 to 3 than those calculated using bulk phonons. A surface Debye temperature is deduced that is about .7 to .8 of the bulk Debye temperature.     

Tensor force and Debye screening in quarkonium-type mesons

We use a non-relativistic quantum-mechanical model to investigate the effect of a screening plama on two quarkonium-type mesons: the charmonium and the bottonium. The stability of these mesons in the plasma is estimated in two cases: including the tensor and spin-orbit term in the potential and without these terms. It turns out that while the bottonium is somewhat stabilized by the tensor force, the charmonium becomes less stabil due to this modification of the potential. Thus the charmonium seems to be a more sensitive probe of the quark-gluon plasma formation than it was thought to be without including the tensor force.     

Modified Debye screening potential in a magnetized quantum plasma

The effects of quantum mechanical influence and uniform static magnetic field on the Shukla-Nambu-Salimullah potential in an ultracold homogeneous electron-ion Fermi plasma have been examined in detail. It is noticed that the strong quantum effect arising through the Bohm potential and the ion polarization effect can give rise to a new oscillatory behavior of the screening potential beyond the shielding cloud which could explain a new type of possible robust ordered structure formation in the quantum magnetoplasma. However, the magnetic field enhances the Debye length perpendicular to the magnetic field in the weak quantum limit of the quantum plasma.     

On the next-to-leading order Debye screening mass in QGP

The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations.     

On the next-to-leading order Debye screening mass in QGP

The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations.     

Absence of Debye screening in the quantum Coulomb system

We present an approximation to the quantum Coulomb plasma at equilibrium which captures the power-law violations of Debye screening which have been reported in recent papers. The objectives are (1) to produce a simpler model which we will study in forthcoming papers, and (2) to develop a strategy by which the absence of screening can be proven for the low-density quantum Coulomb plasma itself.     

德拜模型和自洽场离子球模型屏蔽效应的比较

本文分别用德拜模型和自洽场离子球模型研究了等离子体中类氦铝离子1snp [n=2-3](~1P_1)原子态的能级移动量随电子密度的变化规律,并对二者所计算的能级移动量进行了比较.结果表明:能级移动量随着耦合强度的增大而增大;当耦合强度为一定值时,能级移动量随着电子密度的升高而增大.当电子密度小于1.0×10~(23) cm~(-3)时,不同耦合强度下德拜模型和自洽场离子球模型所计算的能级移动量几乎是相同的.当电子密度大于1.0×10~(23) cm~(-3)时,随着耦合强度的增大,1s2p (~1P_1)原子态的德拜模型的能级移动量由小于自洽场离子球模型的能级移动量,逐渐转变为大于自洽场离子球模型的能级移动量;1s3p (~1P_1)原子态的德拜模型的能级移动量始终小于自洽场离子球模型的能级移动量.     

Debye screening for jellium and other Coulomb systems

Debye screening is proven for a large class of classical Coulomb gases at low densities. Among the models treated are jellium systems (where particles interact with a fixed background charge), systems with arbitrarily dilute fractional charges, and systems where the charges are not integrally related. The interaction potentials of the corresponding sine-Gordon models may have no symmetry and can have infinitely many stationary points which are degenerate or nearly degenerate in energy.Junior Fellow, Harvard University Society of Fellows. Supported in part by the National Science Foundation under Grant No. PHY79-16812     

On the chromo-electric permittivity and Debye screening in hot QCD

We study the response functions (chromo-electric susceptibilities) for an interacting quark-gluon plasma. The interaction effects have been encoded in the effective fugacities for quasi-partons which are extracted self-consistently from the two equations of state for hot QCD. The first one is the fully perturbative O(g ⁵) EOS and the second one, which is O(g ⁶ln(1/g)) , incorporates some non-perturbative effects. We find that the response function shows large deviations from the ideal behavior. We further determine the temperature dependence of the Debye mass by fixing the effective coupling constant Q² which appears in the transport equation. We show that our formalism naturally yields the leading-order HTL expression for the Debye mass if we employ the ideal EOS. Employing the Debye mass, we estimate the dissociation temperatures for various charmonium and bottomonium bound states. These results are consistent with the current theoretical studies.     

Debye screening for two-dimensional Coulomb systems at high temperatures

The grand canonical ensemble of a two-dimensional Coulomb system with±1 charges is proved to have screening phenomena in its high-temperature region. The Coulomb potential in a finite region is assumed to be (–)^–1, where is the Laplacian with zero boundary conditions on. The hard-core condition is not assumed. The model is set up by separating (–)^–1 into a shortrange part and a long-range part depending on a parameter. The self-energies are subtracted only for the short-range part and therefore a choice of is a choice of subtraction of self-energies. The method of proof is in general the same as that of Brydges-Federbush Debye screening, except that here a modification for the short-range part of the potentials is needed.     

A rigorous approach to Debye screening in dilute classical coulomb systems

The existence and exponential clustering of correlation functions for a dilute classical coulomb system are proven using methods from constructive quantum field theory, the sine gordon transformation and the Glimm, Jaffe, Spencer expansion about mean field theory. This is a vindication of a belief, of long standing amongst physicists, known as Debye screening. This states that, because of special properties of the coulomb potential, the configurations of significant probability are those in which the long range parts ofr ^–1 are mostly cancelled, leaving an effective exponentially decaying potential acting between charge clouds.Supported by N.S.F. Grant PHY 76-17191     

The hydrogen atom confined in both Debye screening potential and impenetrable spherical box

The ground state energy, some low-lying excited state energies and oscillator strengths for a hydrogen atom confined in both a Debye screening potential and finite impenetrable spherical box have been calculated. These have been calculated using a linear variational method based on B-spline basis functions. The results have been compared with those of other authors. The evaluated energies and oscillator strengths with respect to different plasma screening parameters with a certain confinement radii are discussed.     

Temperature dependence of the Debye screening length in heavily doped semiconductors having Gaussian band-tails

In the present work, a generalized expression is derived for the Debye screening length of the carriers in heavily doped semiconductors having Gaussian band-tails. The temperature dependence of the screening length is also computed for such semiconductors, taking n-type GaAs as an example.On leave of absence fromthe Department of Physics, B. N. College, University of Patna, India.     

On the oscillatory nature of the Debye screening length in degenerate semiconductors under magnetic quantization

The nature of the magnetic field dependence of the Debye screening length in degenerate semiconductors is shown to be oscillatory under the influence of magnetic quantization.