Search results for "BAND"
showing 10 items of 2610 documents
Dependence of the lattice parameters and the energy gap of zinc-blende-type semiconductors on isotopic masses.
1996
The dependence of the ${\mathit{E}}_{0}$ direct gap of Ge, GaAs, and ZnSe on isotopic masses at low temperatures has been investigated. Contributions of the variation of the lattice parameter to the gap shift of the binary compounds have been evaluated by using a volume-dependent lattice dynamics, while local empirical pseudopotential techniques have been employed to calculate gap shifts due to electron-phonon interaction. The dependence of these terms on the lattice-dynamical model and on the q\ensuremath{\rightarrow}0 extrapolation of the pseudopotential form factors has been investigated. The contributions of the optical and acoustical modes to the isotopic shift are analyzed. The result…
A New Approach to Deriving Interatomic Many-Body Interactions in Metals
1998
An original method of treating the kinetic and exchange-correlation en- ergies functionals in terms of many particle interactions was developed. It is based on utilizing the local density approximation. The total electron density, extracted from the ab initio . band structure calculations, is expressed as a lin- ear superposition of contributions from the individual pseudoions embedded in the uniform background. The explicit expressions for the pair and triplet potentials are presented. The general form for the part of the pair interatomic interactions caused by the kinetic and. the exchange-correlation effects is ob- tained. Relationship between the developing approach and the perturbation…
Testing for public debt sustainability using band spectrum regression analysis "
2014
In this note we focus on the response of the primary surplus to debt (ratios to GDP)over a low frequency band (associated with cycles with period between eight and sixteen years) to filter out business cycle effects. For this purpose, we use band spectrum regression, using both the Fourier Transform and the Discrete Wavelet transform, fitted to pooled panel dataset of 18 EMU countries. The empirical findings give evidence of fiscal fatigue within Eurozone:the response of primary surplus to debt will decrease over a finite debt limit.
Research Direction for Developing an Infrastructure for Mobile & Wireless Systems: Consensus Report of the NSF Workshop Held on October 15, 2001 …
2002
The recent NSF Workshop on Infrastructure for Mobile and Wireless Systems, held on Oct. 15, 2001 in Phoenix had a goal of defining and establishing a common infrastructure for the discipline of mobile wireless networking. This consensus-based paper is the outcome of that workshop. The paper provides a foundation for implementation, standardization, and further research and discussion on the issues of what should constitute such an infrastructure. Workshop participants came from many different wireless communities, including those of communications, operating systems, core networking, mobility, databases, and middleware. The workshop presented various research directions in the field and inc…
Bidirectional Glenn and antegrade pulmonary blood flow: temporary or definitive palliation?
2008
Background We sought to investigate the role of the bidirectional Glenn with antegrade pulmonary blood flow in the surgical history of children with univentricular hearts. Methods A series of 246 patients, from three joint institutions, having univentricular heart with restricted but not critical pulmonary blood flow received a bidirectional cavopulmonary shunt with additional forward pulmonary blood flow. All patients have been studied according to their progression, or not, to Fontan operation. Two hundred and eight (84.5%) patients underwent bidirectional cavopulmonary anastomosis as primary palliation. Twenty patients (8.1%) with previous pulmonary artery banding were also enrolled in t…
An Improved Iterative Nonlinear Least Square Approximation Method for the Design of SISO Wideband Mobile Radio Channel Simulators
2012
In this paper, we present an improved version of the iterative nonlinear least square approximation (INLSA) method for designing measurement-based single-input single-output (SISO) wideband channel simulators. The proposed method aims to fit the time-frequency correlation function (TFCF) of the simulation model to that of a measured channel. The parameters of the simulation model are determined iteratively by minimizing the Frobenius norm, which serves as a measure for the fitting error. In contrast to the original INLSA method, the proposed approach provides a unique optimized set of model parameters, which guarantees a quasi-perfect fitting with respect to the TFCF. We analyze the perform…
A theoretical study of the low-lying excited states of thieno[3,4-b]pyrazine
2009
The low-lying electronic excited states of thieno[3,4-b]pyrazine have been studied using the multiconfigurational second-order perturbation CASPT2 theory with extended atomic natural orbital basis sets. The CASPT2 results allow for a full interpretation of the electronic absorption and emission spectra and provide valuable information for the rationalization of the experimental data. The nature, position, and intensity of the spectral bands have been analyzed in detail. A preliminary comparative study of the ground-state geometry of thieno[3,4-b]pyrazine has been performed at the coupled cluster single and doubles and density functional theory levels using a variety of correlation-consisten…
Infrared bandshapes of intramolecularly H-bonded systems—III. Vibrational dephasing of vs (OH) in 2,6-dichlorophenol
1987
Abstract The shape of the v s (OH) absorption band of intramolecularly H-bonded 2,6-dichlorophenol was measured in a series of solvents of increasing polarity and quantitatively analyzed. A distinct dependence of band positions, shape parameters, band moments, integrated intensities, correlation functions and correlation times on the polarity of solvent has been found. Vibrational dephasing due to dipole—dipole interactions seems to be an important relaxation pathway determining the bandshape in the studied systems.
Local dynamics of DNA probed with optical absorption spectroscopy of bound ethidium bromide
1997
We have studied the local dynamics of calf thymus double-helical DNA by means of an "optical labeling" technique. The study has been performed by measuring the visible absorption band of the cationic dye ethidium bromide, both free in solution and bound to DNA, in the temperature interval 360-30 K and in two different solvent conditions. The temperature dependence of the absorption line shape has been analyzed within the framework of the vibronic coupling theory, to extract information on the dynamic properties of the system; comparison of the thermal behavior of the absorption band of free and DNA-bound ethidium bromide gave information on the local dynamics of the double helix in the prox…
Electronic structure, lattice dynamics and thermodynamic stability of paramelaconite Cu4O3
2014
Abstract An ab initio study of the electronic structure, lattice dynamic and thermodynamic properties of paramelaconite Cu 4 O 3 is reported. The insulating, mixed-valence character of Cu 4 O 3 is elucidated by analyzing the band structure and the spin-orbital symmetry of the Cu-3 d hole states. Exchange coupling constants between Cu 2+ ions are computed which confirm the frustrated antiferromagnetism of the spin lattice. The lattice dynamics is studied from first principles and main features of the vibrational spectrum are assigned to the different chemical species Cu + , Cu 2+ and O. The thermodynamic stability of Cu 4 O 3 is investigated by calculating the free energy of the decompositio…