3,747 research outputs found

    Fluctuations of the inverse participation ratio at the Anderson transition

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    Statistics of the inverse participation ratio (IPR) at the critical point of the localization transition is studied numerically for the power-law random banded matrix model. It is shown that the IPR distribution function is scale-invariant, with a power-law asymptotic ``tail''. This scale invariance implies that the fractal dimensions DqD_q are non-fluctuating quantities, contrary to a recent claim in the literature. A recently proposed relation between D2D_2 and the spectral compressibility χ\chi is violated in the regime of strong multifractality, with χ→1\chi\to 1 in the limit D2→0D_2\to 0.Comment: 4 pages, 3 eps figure

    Zero-bias molecular electronics: Exchange-correlation corrections to Landauer's formula

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    Standard first principles calculations of transport through single molecules miss exchange-correlation corrections to the Landauer formula. From Kubo response theory, both the Landauer formula and these corrections in the limit of zero bias are derived and calculations are presented.Comment: 4 pages, 3 figures, final version to appear in Phys. Rev. B, Rapid Communication

    Wave function statistics at the symplectic 2D Anderson transition: bulk properties

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    The wavefunction statistics at the Anderson transition in a 2d disordered electron gas with spin-orbit coupling is studied numerically. In addition to highly accurate exponents (α0=2.172±0.002,τ2=1.642±0.004\alpha_0{=}2.172\pm 0.002, \tau_2{=}1.642\pm 0.004), we report three qualitative results: (i) the anomalous dimensions are invariant under q→(1−q)q\to (1-q) which is in agreement with a recent analytical prediction and supports the universality hypothesis. (ii) The multifractal spectrum is not parabolic and therefore differs from behavior suspected, e.g., for (integer) quantum Hall transitions in a fundamental way. (iii) The critical fixed point satisfies conformal invariance.Comment: 4 pages, 3 figure

    Universality of the edge tunneling exponent of fractional quantum Hall liquids

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    Recent calculations of the edge tunneling exponents in quantum Hall states appear to contradict their topological nature. We revisit this issue and find no fundamental discrepancies. In a microscopic model of fractional quantum Hall liquids with electron-electron interaction and confinement, we calculate the edge Green's function via exact diagonalization. Our results for ν=1/3\nu = 1/3 and 2/3 suggest that in the presence of Coulomb interaction, the sharpness of the edge and the strength of the edge confining potential, which can lead to edge reconstruction, are the parameters that are relevant to the universality of the electron tunneling I-V exponent.Comment: 5 pages, 3 figure

    The IDEAL (Integrated Design and Engineering Analysis Languages) modeling methodology: Capabilities and Applications

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    The IDEAL (Integrated Design and Engineering Analysis Languages) modeling methodology has been formulated and applied over a five-year period. It has proven to be a unique, integrated approach utilizing a top-down, structured technique to define and document the system of interest; a knowledge engineering technique to collect and organize system descriptive information; a rapid prototyping technique to perform preliminary system performance analysis; and a sophisticated simulation technique to perform in-depth system performance analysis
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