20,556 research outputs found
Landau Fermi Liquid Picture of Spin Density Functional Theory: Strutinsky Approach to Quantum Dots
We analyze the ground state energy and spin of quantum dots obtained from
spin density functional theory (SDFT) calculations. First, we introduce a
Strutinsky-type approximation, in which quantum interference is treated as a
correction to a smooth Thomas-Fermi description. For large irregular dots, we
find that the second-order Strutinsky expressions have an accuracy of about 5
percent compared to the full SDFT and capture all the qualitative features.
Second, we perform a random matrix theory/random plane wave analysis of the
Strutinsky SDFT expressions. The results are statistically similar to the SDFT
quantum dot statistics. Finally, we note that the second-order Strutinsky
approximation provides, in essence, a Landau Fermi liquid picture of spin
density functional theory. For instance, the leading term in the spin channel
is simply the familiar exchange constant. A direct comparison between SDFT and
the perturbation theory derived ``universal Hamiltonian'' is thus made
possible.Comment: Submitted to Physical Review
Electron-Electron Interactions in Isolated and Realistic Quantum Dots: A Density Functional Theory Study
We use Kohn-Sham spin-density-functional theory to study the statistics of
ground-state spin and the spacing between conductance peaks in the Coulomb
blockade regime for both 2D isolated and realistic quantum dots. We make a
systematic investigation of the effects of electron-electron interaction
strength and electron number on both the peak spacing and spin distributions. A
direct comparison between the distributions from isolated and realistic dots
shows that, despite the difference in the boundary conditions and confining
potential, the statistical properties are qualitatively the same. Strong
even/odd pairing in the peak spacing distribution is observed only in the weak
e-e interaction regime and vanishes for moderate interactions. The probability
of high spin ground states increases for stronger e-e interaction and seems to
saturate around . The saturated value is larger than previous
theoretical predictions. Both spin and conductance peak spacing distributions
show substantial variation as the electron number increases, not saturating
until . To interpret our numerical results, we analyze the spin
distribution in the even case using a simple two-level model.Comment: 10 pages, 12 figures, submitted to Phys. Rev.
Adaptive low rank and sparse decomposition of video using compressive sensing
We address the problem of reconstructing and analyzing surveillance videos
using compressive sensing. We develop a new method that performs video
reconstruction by low rank and sparse decomposition adaptively. Background
subtraction becomes part of the reconstruction. In our method, a background
model is used in which the background is learned adaptively as the compressive
measurements are processed. The adaptive method has low latency, and is more
robust than previous methods. We will present experimental results to
demonstrate the advantages of the proposed method.Comment: Accepted ICIP 201
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