205 research outputs found
Anomalous magnetophotoluminescence as a result of level repulsion in arrays of quantum dots
Selectively excited photoluminescence (SPL) of an array of self-organized
InGaAs quantum dots has been measured in a magnetic field up to
11T. Anomalous magnetic field sensitivity of the SPL spectra has been observed
under conditions for which the regular photoluminescence spectra is insensitive
to the magnetic field due to large inhomogeneous broadening. The anomalous
sensitivity is interpreted in terms of the repulsion of excited levels of the
dots in a random potential. A theory presented to describe this phenomena is in
excellent agreement with the experimental data. The data estimated the
correlation in the positions of excited levels of the dots to be 94%. The
magnetic field dependence allows the determination of the reduced cyclotron
effective mass in a dot. For our sample we have obtained
.Comment: 12 revtex preprint pages + 4 ps figures, uuencode
Unusual metallic phase in a chain of strongly interacting particles
We consider a one-dimensional lattice model with the nearest-neighbor
interaction and the next-nearest neighbor interaction with filling
factor 1/2 at zero temperature. The particles are assumed to be spinless
fermions or hard-core bosons. Using very simple assumptions we are able to
predict the basic structure of the insulator-metal phase diagram for this
model. Computations of the flux sensitivity support the main features of the
proposed diagram and show that the system maintains metallic properties at
arbitrarily large values of and along the line ,
where is the hopping amplitude, and . We think that close
to this line the system is a ``weak'' metal in a sense that the flux
sensitivity decreases with the size of the system not exponentially but as
with .Comment: To appear in J. Phys. C; 9 revtex preprint pages + 4 ps figures,
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Analytic Coulomb matrix elements in the lowest Landau level in disk geometry
Using Darling's theorem on products of generalized hypergeometric series an
analytic expression is obtained for the Coulomb matrix elements in the lowest
Landau level in the representation of angular momentum. The result is important
in the studies of Fractional Quantum Hall effect (FQHE) in disk geometry.
Matrix elements are expressed as simple finite sums of positive terms,
eliminating the need to approximate these quantities with slowly-convergent
series. As a by-product, an analytic representation for certain integals of
products of Laguerre polynomials is obtained.Comment: Accepted to J. Math. Phys.; 3 pages revtex, no figure
Rules for Minimal Atomic Multipole Expansion of Molecular Fields
A non-empirical minimal atomic multipole expansion (MAME) defines atomic
charges or higher multipoles that reproduce electrostatic potential outside
molecules. MAME eliminates problems associated with redundancy and with
statistical sampling, and produces atomic multipoles in line with chemical
intuition.Comment: 3.5 pages, 3 color PS figures embedde
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