97,629 research outputs found
Recurrence Formulas for Fully Exponentially Correlated Four-Body Wavefunctions
Formulas are presented for the recursive generation of four-body integrals in
which the integrand consists of arbitrary integer powers (>= -1) of all the
interparticle distances r_ij, multiplied by an exponential containing an
arbitrary linear combination of all the r_ij. These integrals are
generalizations of those encountered using Hylleraas basis functions, and
include all that are needed to make energy computations on the Li atom and
other four-body systems with a fully exponentially correlated Slater-type basis
of arbitrary quantum numbers. The only quantities needed to start the recursion
are the basic four-body integral first evaluated by Fromm and Hill, plus some
easily evaluated three-body "boundary" integrals. The computational labor in
constructing integral sets for practical computations is less than when the
integrals are generated using explicit formulas obtained by differentiating the
basic integral with respect to its parameters. Computations are facilitated by
using a symbolic algebra program (MAPLE) to compute array index pointers and
present syntactically correct FORTRAN source code as output; in this way it is
possible to obtain error-free high-speed evaluations with minimal effort. The
work can be checked by verifying sum rules the integrals must satisfy.Comment: 10 pages, no figures, accepted by Phys. Rev. A (January 2009
Acousto-optic filter for electronic laser tuning
Electronically tunable lithium niobate filter utilizes acoustic-optic diffraction for tuning laser to desired frequencies. Filter placed inside laser cavity diffracts incident optical signal of one polarization into orthogonal polarization by collinearly propagating acoustic beam to desired wavelength
Can Multiband Observations Constrain Explanations for Knotty Jets?
One can imagine a number of mechanisms that could be the cause of
brighter/fainter segments of jets. In a sense, jets might be easier to
understand if they were featureless. However we observe a wide variety of
structures which we call "knots". By considering the ramifications of the
various scenarios for the creation of knots, we determine which ones or which
classes are favored by the currently available multiwavelength data.Comment: 8 pages, to appear in the proceedings of "High Energy Phenomena In
Relativistic Outflows II" (Buenos Aires, Argentina, October 26-30, 2009)
International Journal of Modern Physics D. The editors of the special journal
issue will be G.E. Romero, F.A. Aharonian and J.M. Parede
Proposed acousto-optic filter
Narrow band optical filter is electronically tunable over a large wavelength region. The filter utilizes collinear acousto-optic diffraction in an optically anisotropic media
On the adjoint representation of and the Fibonacci numbers
We decompose the adjoint representation of by a purely combinatorial approach based on the
introduction of a certain subset of the Weyl group called the \emph{Weyl
alternation set} associated to a pair of dominant integral weights. The
cardinality of the Weyl alternation set associated to the highest root and zero
weight of is given by the Fibonacci number. We
then obtain the exponents of from this point of view.Comment: 9 page
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