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Condensed Matter papers — page 180

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Band structures and optical properties of GaInAs quantum wires grown by strain-induced lateral ordering
Band structures and optical matrix elements of strained multiple quantum-wires (QWR's) are investigated theoretically via the effective bond-orbital model, which takes into account the effects of…
Liang-Xin Li, Yia-Chung ChangMay 1, 1998
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The physics of dynamical atomic charges: the case of ABO3 compounds
Based on recent first-principles computations in perovskite compounds, especially BaTiO3, we examine the significance of the Born effective charge concept and contrast it with other atomic charge…
Ph. Ghosez, J. P. Michenaud, X. GonzeMay 1, 1998
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First-principles computation of the Born effective charges and their band-by-band decomposition
The Born effective charge, Z*, that describes the polarization created by collective atomic displacements, can be computed from first-principles by different techniques. Its band-by-band…
Ph. Ghosez, X. GonzeMay 1, 1998
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Perturbative renormalization of multi-channel Kondo-type models
The poor man's scaling is extended to higher order by the use of the open-shell Rayleigh-Schroedinger perturbation theory. A generalized Kondo-type model with the SU(n) times SU(m) symmetry is…
Yoshio KuramotoMay 1, 1998
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The Path Integral Monte Carlo Calculation of Electronic Forces
We describe a method to evaluate electronic forces by Path Integral Monte Carlo (PIMC). Electronic correlations, as well as thermal effects, are included naturally in this method. For fermions, a…
Fenghua Zong, D. M. CeperleyApr 30, 1998
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Pseudogap in 1d revisited
Two decades ago, Sadovskii found an exact solution of a model describing a pseudogap in electron energy spectrum (first introduced by Lee, Rice and Anderson). The discovery of a pseudogap in high-Tc…
Oleg TchernyshyovApr 29, 1998
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Vortex vs spinning string: Iordanskii force and gravitational Aharonov-Bohm effect
We discuss the transverse force acting on the spinning cosmic string, moving in the background matter. It comes from the gravitational Aharonov-Bohm effect and corresponds to the Iordanskii force…
G. E. VolovikApr 29, 1998
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Identification of relaxation and diffusion mechanisms in amorphous silicon
The dynamics of amorphous silicon at low temperatures can be characterized by a sequence of discrete activated events, through which the topological network is locally reorganized. Using the…
G. T. Barkema, Normand MousseauApr 29, 1998
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Monte Carlo Eigenvalue Methods in Quantum Mechanics and Statistical Mechanics
In this review we discuss, from a unified point of view, a variety of Monte Carlo methods used to solve eigenvalue problems in statistical mechanics and quantum mechanics. Although the applications…
M. P. Nightingale, C. J. UmrigarApr 27, 1998
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Nonequilibrium spin distribution in single-electron transistor
Single-electron transistor with ferromagnetic outer electrodes and nonmagnetic island is studied theoretically. Nonequilibrium electron spin distribution in the island is caused by tunneling current.…
Alexander N. Korotkov, V. I. SafarovApr 27, 1998
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New phenomena in the random field Ising model
We reconsider Ising spins in a Gaussian random field within the replica formalism. The corresponding continuum model involves several coupling constants beyond the single one which was considered in…
E. Brézin, C. De DominicisApr 24, 1998
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Near Resonant Spatial Images of Confined Bose-Einstein Condensates in the '4D' Magnetic Bottle
We present quantitative measurements of the spatial density profile of Bose-Einstein condensates of sodium atoms confined in a new '4D' magnetic bottle. The condensates are imaged in…
Lene Vestergaard Hau, B. D. Busch, Chien Liu et al.Apr 24, 1998
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Cold Atoms and Creation of New States of Matter: Bose-Einstein Condensates, Kapitza States, and '2D Magnetic Hydrogen Atoms'
We have succeded in creating Bose-Einstein condensates with 2 million sodium atoms in a '4D' magnetic trap. We show the dynamic formation of a condensate as evaporative cooling proceeds. We…
Lene Vestergaard Hau, B. D. Busch, Chien Liu et al.Apr 24, 1998
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Analytical Results For The Steady State Of Traffic Flow Models With Stochastic Delay
Exact mean field equations are derived analytically to give the fundamental diagrams, i.e., the average speed - car density relations, for the Fukui-Ishibashi one-dimensional traffic flow cellular…
Bing-Hong Wang, Lei Wang, P. M. Hui et al.Apr 24, 1998
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On the High-Pressure Phase Transition in GaPO4
X-ray diffraction (XRD) experiments have been carried out on quartz-like GaPO4 at high pressure and room temperature. A transition to a high pressure disordered crystalline form occurs at 13.5 GPa.…
James Badro, Jean-Paul Itie, Alain PolianApr 23, 1998
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Brownian motion model of random matrices revisited
We present a modified Brownian motion model for random matrices where the eigenvalues (or levels) of a random matrix evolve in "time" in such a way that they never cross each other's…
Sudhir R. Jain, Zafar AhmedApr 23, 1998
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Phase diagram for Ca1-xYxMnO3 type crystals
We present a simple model to study the electron doped manganese perovskites. The model considers the competition between double exchange mechanism for itinerant electrons and antiferromagnetic…
H. Aliaga, R. Allub, B. AlascioApr 22, 1998
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Heisenberg antiferromagnet on the square lattice for S>=1
Theoretical predictions of a semiclassical method - the pure-quantum self-consistent harmonic approximation - for the correlation length and staggered susceptibility of the Heisenberg antiferromagnet…
Alessandro Cuccoli, Valerio Tognetti, Paola Verrucchi et al.Apr 22, 1998
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Intermolecular bond stability of C60 dimers and 2D pressure-polymerized C60
The thermal stability of C60 dimers and 2D pressure-polymerized C60 is studied using high-resolution capacitance dilatometry. The transformation of both the dimer and the polymer phases back to…
P. Nagel, V. Pasler, S. Lebedkin et al.Apr 22, 1998
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Modeling and manufacturability assessment of bistable quantum-dot cells
We have investigated the behavior of bistable cells made up of four quantum dots and occupied by two electrons, in the presence of realistic confinement potentials produced by depletion gates on top…
M. Governale, M. Macucci, G. Iannaccone et al.Apr 21, 1998
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Marshall's sign rule and DMRG acceleration
In applications of White's Density Matrix Renormalization Group (DMRG) algorithm, computation time is dominated by the diagonalisation of large sparse Hamiltonians by iterative diagonalisation…
U. SchollwoeckApr 21, 1998
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N Fermion Ground State of Calogero-Sutherland Type Models in Two and Higher Dimensions
I obtain the exact ground state of N-fermions in D-dimensions (D ≥ 2) in case the N particles are interacting via long-ranged two-body and three-body interactions and further they are also…
Avinash KhareApr 20, 1998
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Connection between Calogero-Marchioro-Wolfes type few-body models and free oscillators
We establish the exact correspondence of the Calogero-Marchioro-Wolfes model and several of its generalizations with free oscillators. This connection yields the eigenstates and leads to a proof of…
N. Gurappa, Avinash Khare, Prasanta. K. PanigrahiApr 20, 1998
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Impurities and Inelastic Processes in Magnetic Tunnel Junctions
We have studied tunnel magnetoresistance (TMR) in junctions with 3d ferromagnetic electrodes. Previously we predicted that defects in the barrier would result in reduced effective polarization P of…
A. M. Bratkovsky, J. H. NickelApr 19, 1998
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Protein design: A perspective from simple tractable models
We review the recent progress in computational approaches to protein design which builds on advances in statistical-mechanical protein folding theory. In particular, we evaluate the degeneracy of the…
E. I. ShakhnovichApr 17, 1998
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