Ab initio calculation of excitonic effects in the optical spectra of semiconductorsAn ab initio approach to the calculation of excitonic effects in the optical absorption spectra of semiconductors and insulators is formulated. It starts from a quasiparticle bandstructure…Stefan Albrecht, Lucia Reining, Rodolfo Del Sole et al.·Mar 16, 1998SaveLearn
Density of kinks just after a quench in an underdamped systemA quench in an underdamped one dimensional ϕ4 model is studied by analytical methods. The density of kinks just after the transition is proportional to the square root of the rate of the quench…Jacek Dziarmaga·Mar 14, 1998SaveLearn
Normal Modes of a Vortex in a Trapped Bose-Einstein CondensateA hydrodynamic description is used to study the normal modes of a vortex in a zero-temperature Bose-Einstein condensate. In the Thomas-Fermi (TF) limit, the circulating superfluid velocity far from…Anatoly Svidzinsky, Alexander Fetter·Mar 14, 1998SaveLearn
Asymptotically exact solutions of Harper equationWe present asymptotically exact solutions of an incommensurate Harper equation---one-dimensional Schroedinger equation of one particle on a lattice in a cosine potential. The wave functions can be…A. G. Abanov, J. C. Talstra, P. B. Wiegmann·Mar 13, 1998SaveLearn
Stability of Solution of the Nonlinear Schrödinger Equation for the Bose-Einstein CondensationWe investigate the stability of the Bose-Einstein condensate (BEC) the case of atoms with negative scattering lengths at zero temperature using the Ginzburg-Pitaevskii-Gross (GPG) stationary theory.…Yeong E. Kim, Alexander L. Zubarev·Mar 13, 1998SaveLearn
The physical determinants of the thickness of lamellar polymer crystalsBased upon kinetic Monte Carlo simulations of crystallization in a simple polymer model we present a new picture of the mechanism by which the thickness of lamellar polymer crystals is constrained to…Jonathan Doye, Daan Frenkel·Mar 13, 1998SaveLearn
Electron trapping by a current vortexWe investigate an electron in the plane interacting with the magnetic field due to an electric current forming a localized rotationally symmetric vortex. We show that independently of the vortex…F. Bentosela, P. Exner, V. A. Zagrebnov·Mar 13, 1998SaveLearn
Brownian motion in fluctuating periodic potentialsThis work deals with the overdamped motion of a particle in a fluctuating one-dimensional periodic potential. If the potential has no inversion symmetry and its fluctuations are asymmetric and…Enrique Abad, Andreas Mielke·Mar 13, 1998SaveLearn
Bose-Einstein condensation with internal degrees of freedom in alkali atom gasesThe Bogoliubov theory is extended to a Bose-Einstein condensation with internal degrees of freedom, realized recently in 23Na gases where several hyperfine states are simultaneously cooled…Tetsuo Ohmi, Kazushige Machida·Mar 13, 1998SaveLearn
Aging and multiscaling in out of equilibrium dynamical processes in granular mediaIn the framework of recently introduced frustrated lattice gas models, we study the out of equilibrium dynamical processes during the compaction process in granular media. We find…Mario Nicodemi, Antonio Coniglio·Mar 12, 1998SaveLearn
Static and dynamic structure factors in the Haldane phase of the bilinear-biquadratic spin-1The excitation spectra of the T=0 dynamic structure factors for the spin, dimer, and trimer fluctuation operators as well as for the newly defined center fluctuation operator in the one-dimensional…K-H Muetter, A Schmitt, M Karbach et al.·Mar 12, 1998SaveLearn
Thermodynamics of frustrated quantum spin chainsWe apply the transfer matrix DMRG to frustrated quantum spin chains, going down to T=0.025 while being in the thermodynamic limit. The incommensurability problem of exact diagonalization and the…K. Maisinger, U. Schollwoeck·Mar 10, 1998SaveLearn
Solitary waves in clouds of Bose-Einstein condensed atomsWe consider the conditions under which solitary waves can exist in elongated clouds of Bose-Einstein condensed atoms. General expressions are derived for the velocity, characteristic size, and…A. D. Jackson, G. M. Kavoulakis, C. J. Pethick·Mar 10, 1998SaveLearn
Green Function Monte Carlo with Stochastic ReconfigurationA new method for the stabilization of the sign problem in the Green Function Monte Carlo technique is proposed. The method is devised for real lattice Hamiltonians and is based on an iterative…S. Sorella·Mar 10, 1998SaveLearn
Aharonov-Bohm and Aharonov-Casher Effects: Connections to Dynamics of Topological SingularitiesWe analyze the physical processes involved in the Aharonov-Bohm (A-B) and the Aharonov-Casher (A-C) effects, showing that an incomplete A-B effect knowledge can lead a totally wrong conclusion on the…P. Ao, Q. Niu·Mar 10, 1998SaveLearn
Friction on a Quantized Vortex in a SuperfluidWe obtain the explicit expression of the friction on a moving quantized vortex, following the formulation of Thouless, Ao and Niu. It is shown that the friction on a moving vortex is sensitive to…X. -M. Zhu, P. Ao·Mar 8, 1998SaveLearn
On the Incommensurate Phase in Modulated Heisenberg ChainsUsing the density matrix renormalization group method (DMRG) we calculate the magnetization of frustrated S=1/2 Heisenberg chains for various modulation patterns of the nearest neighbour coupling:…F. Schönfeld, G. Bouzerar, G. S. Uhrig et al.·Mar 8, 1998SaveLearn
Effect of umklapp scattering on the magnetic-field-induced spin-density waves in quasi-one-dimensional organic conductorsWe study the effect of umklapp scattering on the magnetic-field-induced spin-density-wave (FISDW) phases which are experimentally observed in the quasi-one-dimensional organic conductors of the…N. Dupuis, V. M. Yakovenko·Mar 7, 1998SaveLearn
Suspension and levitation in nonlinear theoriesI investigate stable equilibria of bodies in potential fields satisfying a generalized Poisson equation: divergence[m(grad phi) grad phi]= source density. This describes diverse systems such as…Mordehai Milgrom·Mar 5, 1998SaveLearn
Dynamically Driven Irreversibility in Many Body Quantum Systems: An experimental approachThe NMR technique allows one to create a non-equilibrium local polarization and to detect its later evolution. By a change of the sign of the effective dipolar Hamiltonian, the apparently diffusive…Gonzalo Usaj, Horacio M. Pastawski, Patricia R. Levstein·Mar 3, 1998SaveLearn
Magnetic Field Induced Charge Instabilities in Weakly Coupled SuperlatticesUsing a time dependent selfconsistent model for vertical sequential tunneling,we study the appearance of charge instabilities that lead to the formation of electric field domains in a weakly coupled…R. Aguado, G. Platero·Mar 3, 1998SaveLearn
Dynamic Spin Correlation Function of the Alternating Spin-1/2 Antiferromagnetic Chain with Competing InteractionsDynamic spin correlation function of the S=1/2 antiferromagnetic spin chain with alternating nearest neighbor and competing next nearest neighbor interactions is studied using the numerical…Shigeyoshi Mori, Isao Harada, Takashi Tonegawa·Mar 2, 1998SaveLearn
Evolution of Hole and Spin Dynamics in High Temperature Superconductors within the Small Hole Density Limit of the t-J ModelThe evolution of hole and spin dynamics in high temperature superconductors is studied within the self-consistent noncrossing approximation of the t-J model in the small hole density limit. As the…Bumsoo Kyung·Mar 2, 1998SaveLearn
Strong Tunneling and Coulomb Blockade in a Single-Electron TransistorWe have developed a detailed experimental study of a single-electron transistor in a strong tunneling regime. Although weakened by strong charge fluctuations, Coulomb effects were found to persist in…D. Chouvaev, L. S. Kuzmin, D. S. Golubev et al.·Mar 2, 1998SaveLearn
Novel classical ground state of a many body system in arbitrary dimensionsThe classical ground state of a D- dimensional many body system with two and three body interactions is studied as a function of the strength of the three body interaction. We prove exactly that…G. Date, Pijush K. Ghosh, M. V. N. Murthy·Feb 27, 1998SaveLearn