150,362 research outputs found
Two-electron bond-orbital model, 2
The two-electron bond-orbital model of tetrahedrally-coordinated solids is generalized and its application extended. All intrabond matrix elements entering the formalism are explicitly retained, including the direct overlap S between the anion and cation sp3 hybrid wavefunctions. Complete analytic results are obtained for the six two-electron eigenvalues and eigenstates of the anion-cation bond in terms of S, one-electron parameters V2 and V3, and two-electron correlation parameters V4, V5 and V6. Refined formulas for the dielectric constant and the nuclear exchange and pseudodipolar coefficients, as well as new expressions for the valence electron density, polarity of the bond and the cohesive energy, are then derived. The theory gives a good account of the experimentally observed trends in all properties considered and approximate quantitative agreement is achieved for the pseudodipolar coefficient
Exponential Convergence Towards Stationary States for the 1D Porous Medium Equation with Fractional Pressure
We analyse the asymptotic behaviour of solutions to the one dimensional
fractional version of the porous medium equation introduced by Caffarelli and
V\'azquez, where the pressure is obtained as a Riesz potential associated to
the density. We take advantage of the displacement convexity of the Riesz
potential in one dimension to show a functional inequality involving the
entropy, entropy dissipation, and the Euclidean transport distance. An argument
by approximation shows that this functional inequality is enough to deduce the
exponential convergence of solutions in self-similar variables to the unique
steady states
Two-electron bond-orbital model, 1
Harrison's one-electron bond-orbital model of tetrahedrally coordinated solids was generalized to a two-electron model, using an extension of the method of Falicov and Harris for treating the hydrogen molecule. The six eigenvalues and eigenstates of the two-electron anion-cation Hamiltonian entering this theory can be found exactly general. The two-electron formalism is shown to provide a useful basis for calculating both non-magnetic and magnetic properties of semiconductors in perturbation theory. As an example of the former, expressions for the electric susceptibility and the dielectric constant were calculated. As an example of the latter, new expressions for the nuclear exchanges and pseudo-dipolar coefficients were calculated. A simple theoretical relationship between the dielectric constant and the exchange coefficient was also found in the limit of no correlation. These expressions were quantitatively evaluated in the limit of no correlation for twenty semiconductors
A Study of Anyon Statistics by Breit Hamiltonian Formalism
We study the anyon statistics of a dimensional Maxwell-Chern-Simons
(MCS) gauge theory by using a systemmetic metheod, the Breit Hamiltonian
formalism.Comment: 25 pages, LATE
Orbital Symmetry and Electron Correlation in Na_{x}CoO_2
Measurements of polarization-dependent soft x-ray absorption reveal that the
electronic states determining the low-energy excitations of NaCoO
have predominantly symmetry with significant O character. A large
transfer of spectral weight observed in O x-ray absorption provides
spectral evidence for strong electron correlations in the layered cobaltates.
Comparing Co x-ray absorption with calculations based on a cluster model,
we conclude that NaCoO exhibits a charge-transfer electronic
character rather than a Mott-Hubbard character
Real time hand gesture recognition including hand segmentation and tracking
In this paper we present a system that performs automatic gesture recognition. The system consists of two main components: (i) A unified technique for segmentation and tracking of face and hands using a skin detection algorithm along with handling occlusion between skin objects to keep track of the status of the occluded parts. This is realized by combining 3 useful features, namely, color, motion and position. (ii) A static and dynamic gesture recognition system. Static gesture recognition is achieved using a robust hand shape classification, based on PCA subspaces, that is invariant to scale along with small translation and rotation transformations. Combining hand shape classification with position information and using DHMMs allows us to accomplish dynamic gesture recognition
LLV - Lunar Logistic Vehicle Final report
Evaluation of systems design training institute for engineering facult
From insulator to quantum Hall liquid at low magnetic fields
We have performed low-temperature transport measurements on a GaAs
two-dimensional electron system at low magnetic fields. Multiple
temperature-independent points and accompanying oscillations are observed in
the longitudinal resistivity between the low-field insulator and the quantum
Hall (QH) liquid. Our results support the existence of an intermediate regime,
where the amplitudes of magneto-oscillations can be well described by
conventional Shubnikov-de Haas theory, between the low-field insulator and QH
liquid.Comment: Magneto-oscillations governed by Shubnikov-de Haas theory are
observed between the low-field insulator and quantum Hall liqui
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