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Sum Rules (sum + rule)

Distribution by Scientific Domains

Physics and Astronomy	66%

Distribution within Physics and Astronomy

General & Introductory Physics	66%
Solid State Physics	33%

Selected Abstracts

Sum rules and exact relations for quantal Coulomb systems

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2003
V.M. Adamyan
Abstract A complex response function describing a reaction of a multi-particle system to a weak alternating external field is the boundary value of a Nevanlinna class function (i.e. a holomorphic function with non-negative imaginary part in the upper half-plane). Attempts of direct calculations of response functions based on standard approximations of the kinetic theory for real Coulomb condensed systems often result in considerable discrepancies with experiments and computer simulations. At the same time a relatively simple approach using only the exact values of leading asymptotic terms of the response function permits to restrict essentially a subset of Nevanlinna class functions containing this response function, and in this way to obtain sufficient data to explain and predict experimental results. Mathematical details of this approach are demonstrated on an example with the response function being the (external) dynamic electrical conductivity of cold dense hydrogen-like plasmas. In particular, the exact values of the leading terms of asymptotic expansions of the conductivity are calculated. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optical properties of pure and transition metal-doped indium oxide

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2009
H. A. Rahnamaye Aliabad
Abstract The band structure, the dielectric function, the reflectivity, the refractive index and the oscillator strength sum rule were calculated for pure In2O3 and alloyed In1.5T0.5O3 (where T represents Sc, Y, La and Ac) using density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method was used with the local density approximation (LDA + U). Calculations of the optical spectra were performed for the energy range 0,30 eV. The calculated results indicate that the upper valance bands of In2O3 show a small dispersion and the value of the band gap increases for Sc and Y dopants and decreases for Ac and La dopants. The calculations indicate that there are two band gaps for In2O3. The first shows a strong optical absorption, as a direct band gap occurs from a 0.81 eV energy level below the top of valence band. The second shows a much weaker absorption from the top of the valence band to the bottom of the conduction band. The refractive index for In2O3 is 1.69 nm at 800 nm, near the visible region. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Soft X-ray absorption spectroscopy and magnetic circular dichroism study of electroless-deposited CoNiFe ternary alloy soft magnetic films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
Masahito Tanaka
Abstract We studied microscopic magnetic properties of each consistent atom in boron added CoNiFe electroless-deposited soft magnetic films, which is a promising candidate for the soft magnetic underlayer of the perpendicular magnetic recording medium, by X-ray absorption spectra (XAS) and magnetic circular dichroism (MCD) measurement. It was found that various monoxides and Fe sesquioxide coexisted with the metals at the upper part of the films. The results of MCD sum rule showed the expected values of orbital angular moment ,Lz, for the film with macroscopic magnetic domain boundaries were larger than those of without domains at Co and Ni atoms and smaller at Fe atom. The appearance of macroscopic magnetic domain boundaries probably originated from the increase in ,Lz, of Co and/or Ni atoms. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The role of inequalities in the analysis of many-body systems,

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2010
J. K. PercusArticle first published online: 8 SEP 2010
Abstract We discuss the strategy of determining properties of many-body systems by applying successively more stringent limitations on the domain on which solutions can lie, i.e., sharpening the degree of resolution of the results obtained. A rough division is made into universal, or system-independent inequalities and system-dependent ones, which are joined by equalities or sum rules. General examples include Fermion ground states and classical fluids in thermal equilibrium, and for the latter, the effect of estimation by saturating inequalities. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]

Logarithmic perturbation theory for a spiked oscillator and sum rules

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2005
S. K. Bandyopadhyay
Abstract We show that logarithmic perturbation theory nicely yields the wavefunction correction terms in closed forms for the spiked perturbation ,/x2 on the first excited state of the harmonic oscillator, where the conventional Rayleigh-Schrödinger scheme is known to encounter serious problems. The study also provides a direct route to obtain several sum rules, some of which appear to be new. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]

Deep inside the pion.

ANNALEN DER PHYSIK, Issue 11-12 2004
Reconciling QCD theory with data
Abstract Recent developments in the QCD description of the pion structure are reviewed. The CLEO pion-photon transition data analysis favors a distribution amplitude for the pion that is double-humped but endpoint-suppressed. After a short outline of the derivation of this amplitude from QCD sum rules with nonlocal condensates, we present the fully fledged analysis of the CLEO data prefaced by predictions for the F,,, form factor and commenting on the inherent theoretical uncertainties due to higher twists and NNLO perturbative corrections. We supplement our discussion by considering within QCD factorization theory, the electromagnetic pion form factor at NLO accuracy on one hand, and diffractive di-jets production on the other, comparing our predictions with the respective experimental data from JLab and the Fermilab E791 collaboration. In all cases, the agreement is impressive. [source]

The 2-matrix of the spin-polarized electron gas: contraction sum rules and spectral resolutions

ANNALEN DER PHYSIK, Issue 3 2004
P. Ziesche
Abstract The spin-polarized homogeneous electron gas with densities ,, and ,, for electrons with spin ,up' (,) and spin ,down' (,), respectively, is systematically analyzed with respect to its lowest-order reduced densities and density matrices and their mutual relations. The three 2-body reduced density matrices ,,,, ,,,, ,a are 4-point functions for electron pairs with spins ,,, ,,, and antiparallel, respectively. From them, three functions G,,(x,y), G,,(x,y), Ga(x,y), depending on only two variables, are derived. These functions contain not only the pair densities according to g,,(r) = G,uarr;(0,r), g,,(r) = G,,(0,r), ga(r) = Ga(0,r) with r = |r1 - r2|, but also the 1-body reduced density matrices ,, and ,, being 2-point functions according to ,s = ,sfs and fs(r) = Gss(r, ,) with s = ,,, and r = |r1 - r,1|. The contraction properties of the 2-body reduced density matrices lead to three sum rules to be obeyed by the three key functions Gss, Ga. These contraction sum rules contain corresponding normalization sum rules as special cases. The momentum distributions n,(k) and n,(k), following from f,(r) and f,(r) by Fourier transform, are correctly normalized through fs(0) = 1. In addition to the non-negativity conditions ns(k),gss(r),ga(r) , 0 [these quantities are probabilities], it holds ns(k) , 1 and gss(0) = 0 due to the Pauli principle and ga(0) , 1 due to the Coulomb repulsion. Recent parametrizations of the pair densities of the spin-unpolarized homogeneous electron gas in terms of 2-body wave functions (geminals) and corresponding occupancies are generalized (i) to the spin-polarized case and (ii) to the 2-body reduced density matrix giving thus its spectral resolutions. [source]