On potential and field fluctuations in classical charged systems

Using electrostatic identities the potential and microfield in a plasma, important for determining line shapes, are expressed as limits of local quantities. These are shown to be well defined for typical configurations of macroscopic, i.e., infinite systems (under some mild clustering assumptions). Their covariance contains a slowly decaying part (¦x¦^–1, for the potential) whose coefficient is universal whenever the Stillinger-Lovett second moment condition holds. We show further that the contributions from distant regions (which are equal to suitable averages over local regions) have a Gaussian distribution.Supported in part by AFOSR Grant No. 82-0016.Supported in part by the Swiss National Foundation for Scientific Research.     

On potential and field fluctuations in two-dimensional classical charged systems

We supplement a previous paper on three-dimensional systems by studying the electric potential and field fluctuations in two-dimensional Coulomb systems. The novelty in two dimensions is that the fluctuations of the potential at a point are infinite in the thermodynamic limit. However, the potential difference between two points has finite fluctuations, which resemble the ones which occur in the three-dimensional case. The field fluctuations are also rather similar in both cases. The correlations do not have a fast decay. Explicit results are obtained for a solvable model; the fluctuations of the potential are Gaussian with an infinite variance.This laboratory is associated with the Centre National de la Recherche Scientifique.     

Detailed balance and critical slowing down for classical lattice systems

For classical lattice systems we prove rigorously a relation between the fluctuations and the relaxation times for a dynamics given by a detailed balance semigroup. In particular we give a rigorous proof of the conventional theory of critical slowing down.On leave of absence from Institute of Theoretical Physics and Astrophysics, Gdansk University, Poland.     

Cyclic polymers swollen in a good solvent dynamic scattering properties

A general formalism for the dynamic scattering properties of cyclic polymers in good solvent conditions is presented. Single-chain dynamics are investigated in the framework of the Oseen tensor model with and without the preaveraging approximation. The chain swelling due to excluded volume interactions is introduced by a renormalization of the internal chain statistics of cyclic polymers. The relaxations of the concentration fluctuations are also described for both ring homopolymers and copolymers. © 1994 John Wiley & Sons, Inc.     

Specific heat jump in non-Fermi superconductors

We derive the jump in the specific heat at T=T _c for a superconductor in a non-Fermi liquid model. We took into consideration the two possible limits in this problem: the spin-charge separation model for a Fermi liquid and the usual non-Fermi liquid model which satisfies the homogeneity relation for the spectral function , ). We also derive the order parameter behavior for these two cases in the vecinity of the critical temperature. Received: 25 January 1998 / Revised: 25 March 1998 / Accepted: 25 March 1998     

Length-independent voltage fluctuations in small conductors

The mean-squared voltage fluctuation of a disordered conductor of lengthL smaller than the phase coherence lengthL _ϕ, is independent of the distance between the probes. We obtain this result using the voltage additivity and the known results for the conductance fluctuation. Our results complement the recent theoretical and experimental findings.     

Effect of local field fluctuations on orientational ordering in random-site dipole systems

Some peculiarities of dipole ordering in systems with uniaxial or cubic anisotropy with an arbitrary degree of dilution are analyzed in terms of random local field theory. The approach takes into account the effect of thermal and spatial fluctuations of the local fields acting on each particle from its neighbors with an accuracy corresponding to that of the Bethe-Paierls pair clusters approach. We show that ferromagnetic (ferroelectric) structure for uniaxial Ising dipoles distributed on a simple cubic lattice is intrinsically unstable against the fluctuations of the local fields for any concentration of the dipoles. This result is quite different from the prediction of the mean-field theory which implies the possibility of ferromagnetic ordering as a metastable state in field-cooled experiments. The local field fluctuations do not exclude, however, antiferromagnetic ordering above a certain critical concentration. Ferromagnetic ordering is possible for other types of lattice geometries and for an amorphous-like dipole distribution above a certain critical concentration. A simple physical explanation of such behavior is given based on the specific angular dependence of the dipole-dipole interaction that results in a relatively high value of the local field second moment for simple cubic lattice.     

The energy dependence of photoelectron peak intensities,Part I: Experimental methods

With the increasing popularity of synchrotron radiation as a tunable photon source for photoemission spectroscopy, the significance of photoelectron peak variation with photon energy is becoming apparent. This variation is due to a number of intrinsic factors (excitation cross section, photon and electron reflection and refraction, inelastic processes, etc.) as well as instrumental factors (monochromator transmission and spectral purity, electron analyzer transmission and resolution, etc.). In this paper we develop methods for factoring out these contributions with the goal of determining the excitation cross section from a peak area measurement. Parts II and III will deal with a range of cross section measurements, and the use of relative peak area information to determine stoichiometry vs. probe depth.     

Irregular Fluctuations in Uncoupled Map Lattices

Analytic approximations for the spatial average and its variance are derived for a system of N uncoupled chaotic logistic maps with growth parameter r = 4. The arising nontrivial closure problem is investigated with various techniques related to the classical moment problem. A Lyapunov-like linear stability analysis is presented for the transient as well as for the fluctuation regime.