A. Günen

A FINITE-SIZE SCALING STUDY OF THE FOUR-DIMENSIONAL ISING MODEL ON THE CREUTZ CELLULAR AUTOMATON

The four-dimensional Ising model is simulated on the Creutz cellular automaton with increased precision. The data are analyzed according to the finite-size scaling relations available. The precision of the critical values related to magnetic susceptibility is improved by one digit, but in order to reach to the same precision for those related to the specific heat more simulation runs at the critical temperatures of the finite-size lattices are required.

Effect Of The Number Of Energy Levels Of A Demon For The Simulation Of The Four-Dimensional Ising Model On The Creutz Cellular Automaton

The four-dimensional Ising model is simulated on the Creutz cellular automaton by using three- and four-bit demons. The simulations result in overlapping curves for both the order parameter, the magnetic susceptibility, the internal energy and the Binder cumulant. However, the specific heat curves overlap above and at Tc as the number of energy levels of a demon or the number of bits increases, but below Tc they are strongly violated. The critical exponents for the order parameter and the magnetic susceptibility as the number of bits increases are obtained by analyzing the data according to the finite-size scaling relations available.

THE EFFECT OF THE INCREASE OF LINEAR DIMENSIONS ON EXPONENTS OBTAINED BY FINITE-SIZE SCALING RELATIONS FOR THE FOUR-DIMENSIONAL ISING MODEL ON THE CREUTZ CELLULAR AUTOMATON

The four-dimensional Ising model is simulated on the Creutz cellular automaton using finite-size lattices with linear dimension 4 ≤ L ≤ 22. The exponents in the finite-size scaling relations for the order parameter, the magnetic susceptibility at the finite-lattice critical temperature and the specific heat at the infinite-lattice critical temperature are computed to be β = 0.5072(58), γ = 1.0287(56) and α = -0.096(17), respectively, which are consistent with the renormalization group prediction of β = 0.5, γ = 1 and α = 0. The critical temperatures for the infinite lattice are found to be

Three-body effect on the lattice dynamics of some fcc d-band metals

T_c^{\chi}=6.6824(5)

A High Precision Calculation of the Excitation Flux for X-ray Fluorescence Spectroscopy with Cylindrical Geometry

and

CALCULATION OF THE X-RAY FLUORESCENCE INTENSITY AND DETECTOR COUNT RATE FOR ANNULAR SOURCE GEOMETRY

T_c^C=6.6736(27)

Frequency-dependent dielectric characteristics of Tl–Ba–Ca–Cu–O bulk superconductor

, which are also consistent with the precise results.

The Effect of PbSe Addition on the Mechanical Properties of Bi-2212 Superconductors

SummaryIn the present analysis, the interaction system of an fcc d-band metal is considered to be composed of two-body and three-body parts. We use a new three-body potential developed by Akgün and Uğur to deduce the contribution of many-body forces to the dynamical matrix of the fcc structure. Two- and three-body potentials are first used, as an application to investigate the dynamical behaviors of fcc d-band metals, Ni, Pd, Cu and Ag. The parameters defining the two- and three-body potentials for the metals are evaluated from knowledge of the equilibrium pair energies, bulk modulus and total cohesive energies of the metals, following a procedure given by Akgün and Uğur. In this scheme the input data is independent of phonon frequencies and elastic constants of the metals. Finally, the phonon frequencies of the metals along the principal symmetry directions are computed using the calculated radial, tangential and three-body force constants. The theoretical results are compared to experimental phonon dispersions. The agreement shows that the proposed potentials and crystal model provide a reasonable description of the lattice dynamics of fcc d-band metals.

The test of the finite-size scaling relations of the Ising models in seven and eight dimensions on the Creutz cellular automaton

INTRODUCTION Radioisotope-excited X-ray fluorescence is one of the more recent techniques developed that has resulted from the general availability of sealed radionuclide sources. In experimental work, following the excitation of the specimen by X-ray photons, the integrated photo-peak intensity of the characteristic fluorescent line of interest is measured and usually compared with the results of theoretical estimates. Experimental results can be obtained with higher precision due to recent developments in solid state detectors and in the use of computers [1–4]. However, owing to the complexity of the overall exact calculation for X-ray fluorescence systems of given dimensions, theoretical estimates are found to be not of the same precision as that of the experimental results. Prior to reaching the final theoretical estimates of detector count rate, a prerequisite calculation of essential parameters, such as excitation flux and fluorescent intensity variation over the specimen, are required.

Structural and mechanical characterization of Bi1.75Pb0.25Sr2Ca2Cu3−xSnxO10+y superconductor ceramics using Vickers microhardness test

ABSTRACT Expressions for X-ray fluorescence spectroscopy described in a previous paper, were extended for the calculation of the fluorescence intensity of a thin specimen, providing a detector count rate with a precision of better than 0.2%. The results are presented in the form of δ(ζ1η1 − ζ2η2) where η1 and η2 are the standard functions common to all cylindrical geometry systems of any size, δ, and where ζ1, and ζ2 are user calculable coefficients.