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Bound States (bound + states)
Selected AbstractsBound states in the phase diagram of the extended Hubbard modelPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2005M. Bak Abstract The paper shows how the known, exact results for the two electron bound states can modify the ground state phase diagram of extended Hubbard model (EHM) for on-site attraction, intersite repulsion and arbitrary electron density. The main result is suppression of the superconducting state in favor of normal phase for small charge densities. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] How correct is the EOS of weakly nonideal hydrogen plasmas?CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2003A.N. Starostin Abstract Helioseismology opens new possibility to check EOS of weakly nonideal hydrogen plasmas with high precision, using reconstructed local sound velocities within 10-4 accuracy. A comparison of different theoretical models with experiment permits to verify the existing methods of calculation bound states and continuum contribution to the second virial coefficient within the framework of physical nature. The regular way of the deduction expression for EOS is presented and generalization of the EOS for broad atomic states and two temperature non-equilibrium case is proposed. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Yangian symmetry, S-matrices and Bethe ansatz for the AdS5 × S5 superstringFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 5-7 2009M. de Leeuw Abstract We discuss the relation between the recently derived bound state S-matrices for the AdS5× S5 superstring and Yangian symmetry. We will study the relation between this Yangian symmetry and the Bethe ansatz. In particular we can use it to derive the Bethe equations for bound states. [source] Single impurity Anderson model and band anti-crossing in the Ga1,xInx Ny As1,y material systemPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2008Nikolaos Vogiatzis Abstract The role of the single-N impurity in the GaInNAs system is evaluated using the single impurity Anderson model. The N impurities can act either as scattering resonances or as bound states depending on their energy position. For the former case, using self-energy calculations and Matsubara Green's functions we investigate the nature of the mixed single-N state (energy broadening, shift). The effect of this interaction on the perturbed conduction subbands is also examined. The single impurity Anderson model results in a complex band structure. The real part of the band structure can be directly related to the dispersion obtained with the band anti-crossing model and is in very good agreement. The imaginary bandstructure contains further information about the mixing of the nitrogen state and the conduction band which is not contained within the band anti-crossing model. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mixed singlet-triplet superconducting state in doped antiferromagnetsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2006A. Maci¸ag Abstract We analyze symmetry mixing in the superconducting (SC) order parameter of planar cuprates. The behavior of thermal conductivity observed in some systems doped with magnetic impurities or in some systems exposed to external magnetic field seems to indicate that such symmetry mixing takes place. We discuss this phenomenon in the framework of the spin polaron model (SPM). We assume that antiferromagnetic (AF) correlations, which are at least of short range, tend to confine motion of holes which have been created in the AF spin background. The nature of the propagation of quasiparticles which are hole-like and the nature of the interaction between quasiparticles is determined by a tendency to restore the local AF order. It is known that two holes in the t ,J model (tJ M) form bound states with dx 2,y2 or p-wave symmetry. The d-wave bound state has lower energy and is the ground state. The mixing of d-wave symmetry with p-wave symmetry takes place in the SC order parameter at some range of finite values of the doping parameter. That range lies at the applicability verge of the SPM, where AF correlation are already very short. On the other hand, these correlations may be strengthened by above mentioned external factors, which seems to explain why symmetry mixing is observed in this case. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Bound states in the phase diagram of the extended Hubbard modelPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2005M. Bak Abstract The paper shows how the known, exact results for the two electron bound states can modify the ground state phase diagram of extended Hubbard model (EHM) for on-site attraction, intersite repulsion and arbitrary electron density. The main result is suppression of the superconducting state in favor of normal phase for small charge densities. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] First principles approach to binding energies of excitons, trions and biexcitons in quantum wellsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2003A. V. Filinov Abstract We present first-principle path integral Monte-Carlo (PIMC) studies of strongly correlated electron,hole complexes such as excitons, trions (charged excitons) and biexcitons in AlxGa1,xAs quantum-well structures. The correlation and binding energies are calculated as function of quantum well width L, for 10 Å , L , 250 Å and compared with available experimental [1] and theoretical [2,4] data. As in the experiments, we observe a maximum of the binding energies in GaAs/AlGaAs quantum well samples around L = 40 Å the physical reason of which is the non-monotonic dependence of the electron (hole) confinement on the well width. The developed method is a powerful tool for further systematic investigation of the influence of temperature and many-body effects on bound states in heterostructures (e.g. depedence on finite exciton, biexciton densities) and disorder (e.g. well-width fluctuations). [source] Structure determination of a Galectin-3,carbohydrate complex using paramagnetism-based NMR constraintsPROTEIN SCIENCE, Issue 7 2008Tiandi Zhuang Abstract The determination of the location and conformation of a natural ligand bound to a protein receptor is often a first step in the rational design of molecules that can modulate receptor function. NMR observables, including NOEs, often provide the basis for these determinations. However, when ligands are carbohydrates, interactions mediated by extensive hydrogen-bonding networks often reduce or eliminate NOEs between ligand and protein protons. In these cases, it is useful to look to other distance- and orientation-dependent observables that can constrain the geometry of ligand,protein complexes. Here we illustrate the use of paramagnetism-based NMR constraints, including pseudo-contact shifts (PCS) and field-induced residual dipolar couplings (RDCs). When a paramagnetic center can be attached to the protein, field-induced RDCs and PCS reflect only bound-state properties of the ligand, even when averages over small fractions of bound states and large fractions of free states are observed. The effects can also be observed over a long range, making it possible to attach a paramagnetic center to a remote part of the protein. The system studied here is a Galectin-3,lactose complex. A lanthanide-binding peptide showing minimal flexibility with respect to the protein was integrated into the C terminus of an expression construct for the Galectin-3,carbohydrate-binding domain. Dysprosium ion, which has a large magnetic susceptibility anisotropy, was complexed to the peptide, making it possible to observe both PCSs and field-induced RDCs for the protein and the ligand. The structure determined from these constraints shows agreement with a crystal structure of a Galectin-3,N -acetyllactosamine complex. [source] Enhancement of bound-state residual dipolar couplings: Conformational analysis of lactose bound to Galectin-3PROTEIN SCIENCE, Issue 7 2006Tiandi Zhuang Abstract Residual dipolar couplings (RDCs) have proven to be a valuable NMR tool that can provide long-range constraints for molecular structure determination. The constraints are orientational in nature and are, thus, highly complementary to conventional distance constraints from NOE data. This complementarity would seem to extend to the study of the geometry of ligands bound to proteins. However, unlike transferred NOEs, where collection, even with a large excess of free ligand, results in measurements dominated by bound contributions, RDCs of exchanging ligands can be dominated by free-state contributions. Here we present a strategy for enhancement of RDCs from bound states that is based on specifically enhancing the alignment of the protein to which a ligand will bind. The protein is modified by addition of a hydrophobic alkyl tail that anchors it to the bicelles that are a part of the ordering medium needed for RDC measurement. As an illustration, we have added a propyl chain to the C terminus of the carbohydrate recognition domain of the protein, Galectin-3, and report enhanced RDCs that prove consistent with known bound-ligand geometries for this protein. [source] Localised magneto-optical collective excitations of impure grapheneANNALEN DER PHYSIK, Issue 12 2009A.M. Fischer Abstract We study optically-induced collective excitations of graphene in the presence of a strong perpendicular magnetic field and a single impurity. We determine the energies and absorption strengths of these excitations, which become localised on the impurity. Two different types of impurity are considered i. the long-range Coulomb impurity, ii. a ,-function impurity located at either an A or B graphene sublattice site. Both impurity types result in some bound states appearing both above and below the magnetoplasmon continuum, although the effect of the short-range impurity is less pronounced. The dependence of the energies and oscillator strengths of the bound states on the filling factor is investigated. [source] Exact solution of the Klein-Gordon equation for the PT-symmetric generalized Woods-Saxon potential by the Nikiforov-Uvarov methodANNALEN DER PHYSIK, Issue 3 2007S.M. Ikhdair Abstract The exact solution of the one-dimensional Klein-Gordon equation of the ,,,,-symmetric generalized Woods-Saxon potential is obtained. The exact energy eigenvalues and wavefunctions are derived analytically by using the Nikiforov and Uvarov method. In addition, the positive and negative exact bound states of the s-states are also investigated for different types of complex generalized Woods-Saxon potentials. [source] Crystallization and preliminary X-ray crystallographic analysis of Ca2+ -independent and Ca2+ -dependent species of the type II antifreeze proteinACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2006Yoshiyuki Nishimiya Ca2+ -independent and Ca2+ -dependent species of the type II antifreeze protein (AFP) were both crystallized using the hanging-drop vapour-diffusion method. It appeared that the crystal of the Ca2+ -independent species from Brachyosis rostratus belongs to space group P212121, with unit-cell parameters a = 43.3, b = 48.4, c = 59.7,Å, and diffraction data were collected to 1.34,Å resolution. For the Ca2+ -dependent type II AFP species from Hypomesus nipponensis, crystallization was carried out for its Ca2+ -free and Ca2+ -bound states. 1.25,Å resolution data were collected from the crystal in the Ca2+ -free state, which exhibited P3121 (or P3221) symmetry, with unit-cell parameters a = b = 66.0, c = 50.3,Å. Data collection could be extended to 1.06,Å resolution for the crystal in the Ca2+ -bound state, which appeared to be isomorphous to the crystal in the Ca2+ -free state (unit-cell parameters a = b = 66.0, c = 49.8,Å). These data will allow us to determine the high-resolution structures of the two species of type II AFP. [source] | |||||||||||||||||||||||||