31,153 research outputs found

    On the finite termination of an entropy function based smoothing Newton method for vertical linear complementarity problems

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    By using a smooth entropy function to approximate the non-smooth max-type function, a vertical linear complementarity problem (VLCP) can be treated as a family of parameterized smooth equations. A Newton-type method with a testing procedure is proposed to solve such a system. We show that the proposed algorithm finds an exact solution of VLCP in a finite number of iterations, under some conditions milder than those assumed in literature. Some computational results are included to illustrate the potential of this approach.Newton method;Finite termination;Entropy function;Smoothing approximation;Vertical linear complementarity problems

    LDA+Gutzwiller Method for Correlated Electron Systems

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    Combining the density functional theory (DFT) and the Gutzwiller variational approach, a LDA+Gutzwiller method is developed to treat the correlated electron systems from {\it ab-initio}. All variational parameters are self-consistently determined from total energy minimization. The method is computationally cheaper, yet the quasi-particle spectrum is well described through kinetic energy renormalization. It can be applied equally to the systems from weakly correlated metals to strongly correlated insulators. The calculated results for SrVO3_3, Fe, Ni and NiO, show dramatic improvement over LDA and LDA+U.Comment: 4 pages, 3 figures, 1 tabl

    Strong ferromangnetism and weak antiferroamgnetism in double perovskites: Sr2_2Fe{/it M}O6_6 ({/it M}=Mo, W and Re)

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    Double perovskites Sr2_2FeMO6_6 (M=Mo and Re) exhibit significant colossal magnetoresistance even at room temperature due to the high Curie Temperature (419K and 401K). However, such a high Curie Temperature is puzzling, given the large separation between magnetic elements (Fe). Moreover, with M=W, the electronic and magnetic properties suddenly change to insulating and antiferromagnetic with the N{\'e}el temperature of only 16\sim37 K. Based on detailed electronic structure calculations, a new mechanism is proposed which stabilizes the strong ferromagnetic state for M=Mo and Re and is passivated for M=W.Comment: 4 pages, 3 figures; accepted by PRB as rapid communicatio

    Heavy Quark Potentials in Some Renormalization Group Revised AdS/QCD Models

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    We construct some AdS/QCD models by the systematic procedure of GKN. These models reflect three rather different asymptotics the gauge theory beta functions approach at the infrared region, βλ2,λ3\beta\propto-\lambda^2, -\lambda^3 and βλ\beta\propto-\lambda, where λ\lambda is the 't Hooft coupling constant. We then calculate the heavy quark potentials in these models by holographic methods and find that they can more consistently fit the lattice data relative to the usual models which do not include the renormalization group improving effects. But only use the lattice QCD heavy quark potentials as constrains, we cannot distinguish which kind of infrared asymptotics is the better one.Comment: comparisons with lattice results, qualitative consideration of quantum corrections are added. (accepted by Phys. Rev. D

    A relativistic calculation of super-Hubble suppression of inflation with thermal dissipation

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    We investigated the evolution of the primordial density perturbations produced by inflation with thermal dissipation. A full relativistic analysis on the evolution of initial perturbations from the warm inflation era to a radiation-dominated universe has been developed. The emphasis is on tracking the ratio between the adiabatic and the isocurvature mode of the initial perturbations. This result is employed to calculate a testable factor: the super-Hubble suppression of the power spectrum of the primordial perturbations. We show that based on the warm inflation scenario, the super-Hubble suppression factor, ss, for an inflation with thermal dissipation is at least 0.5. This prediction does not depend on the details of the model parameters. If ss is larger than 0.5, it implies that the friction parameter Γ\Gamma is larger than the Hubble expansion parameter HH during the inflation era.Comment: 22 pages, 3 figures, use RevTex, accepted by Class. Quant. Gra
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