2,896 research outputs found
Use of Harmonic Inversion Techniques in the Periodic Orbit Quantization of Integrable Systems
Harmonic inversion has already been proven to be a powerful tool for the
analysis of quantum spectra and the periodic orbit orbit quantization of
chaotic systems. The harmonic inversion technique circumvents the convergence
problems of the periodic orbit sum and the uncertainty principle of the usual
Fourier analysis, thus yielding results of high resolution and high precision.
Based on the close analogy between periodic orbit trace formulae for regular
and chaotic systems the technique is generalized in this paper for the
semiclassical quantization of integrable systems. Thus, harmonic inversion is
shown to be a universal tool which can be applied to a wide range of physical
systems. The method is further generalized in two directions: Firstly, the
periodic orbit quantization will be extended to include higher order hbar
corrections to the periodic orbit sum. Secondly, the use of cross-correlated
periodic orbit sums allows us to significantly reduce the required number of
orbits for semiclassical quantization, i.e., to improve the efficiency of the
semiclassical method. As a representative of regular systems, we choose the
circle billiard, whose periodic orbits and quantum eigenvalues can easily be
obtained.Comment: 21 pages, 9 figures, submitted to Eur. Phys. J.
Photoabsorption spectra of the diamagnetic hydrogen atom in the transition regime to chaos: Closed orbit theory with bifurcating orbits
With increasing energy the diamagnetic hydrogen atom undergoes a transition
from regular to chaotic classical dynamics, and the closed orbits pass through
various cascades of bifurcations. Closed orbit theory allows for the
semiclassical calculation of photoabsorption spectra of the diamagnetic
hydrogen atom. However, at the bifurcations the closed orbit contributions
diverge. The singularities can be removed with the help of uniform
semiclassical approximations which are constructed over a wide energy range for
different types of codimension one and two catastrophes. Using the uniform
approximations and applying the high-resolution harmonic inversion method we
calculate fully resolved semiclassical photoabsorption spectra, i.e.,
individual eigenenergies and transition matrix elements at laboratory magnetic
field strengths, and compare them with the results of exact quantum
calculations.Comment: 26 pages, 9 figures, submitted to J. Phys.
Manganese carbonyl-mediated reactions of azabutadienes with phenylacetylene, methyl acrylate and other unsaturated molecules
Reaction of PhCHâMn(CO)â
with l,4-di-aryl-1-aza-1,3-butadienes gave substituted pyrrolinonyl rings which were ηâŽ-coordinated to a Mn(CO)â group. These are formed by intramolecular CO insertion into a (non-isolated) cyclomanganated intermediate, followed by cyclisation. Other unsaturated reagents (PhCâĄCH, CH2=CHCOOMe, PhNCO) gave products arising from insertion of these, including a structurally characterised tri-aryl-ηâ”-azacyclohexadienyl-Mn(CO)â complex from the reaction with the alkyne.
PhCHâMn(CO)â
reacts with l,4-di-aryl-1-aza-1,3-butadienes in the presence of unsaturated substrates to give products based on a cyclomanganated intermediate
2-(1,4-Dioxo-1,4-dihydro-2-naphthyl)-2-methylpropanoic acid
The sterically crowded title compound, CââHââOâ, crystallizes as centrosymmetric hydrogen-bonded dimers involving the carboxyl groups. The naphthoquinone ring system is folded by 11.5 (1)° about a vector joining the 1,4-C atoms, and the quinone O atoms are displaced from the ring plane, presumably because of steric interactions with the bulky substituent
Semiclassical quantization of the hydrogen atom in crossed electric and magnetic fields
The S-matrix theory formulation of closed-orbit theory recently proposed by
Granger and Greene is extended to atoms in crossed electric and magnetic
fields. We then present a semiclassical quantization of the hydrogen atom in
crossed fields, which succeeds in resolving individual lines in the spectrum,
but is restricted to the strongest lines of each n-manifold. By means of a
detailed semiclassical analysis of the quantum spectrum, we demonstrate that it
is the abundance of bifurcations of closed orbits that precludes the resolution
of finer details. They necessitate the inclusion of uniform semiclassical
approximations into the quantization process. Uniform approximations for the
generic types of closed-orbit bifurcation are derived, and a general method for
including them in a high-resolution semiclassical quantization is devised
Synthesis and alkyne-coupling chemistry of cyclomanganated 1- and 3-acetylindoles, 3-formylindole and analogues
The syntheses are reported of new cyclomanganated indole derivatives (1-acetyl-ÎșO-indolyl-ÎșC2)dicarbonylbis(trimethylphosphite)manganese (2), (1-methyl-3-acetyl-ÎșO-indolyl-ÎșC2)tetracarbonylmanganese (4), (3-formyl-ÎșO-indolyl-ÎșC2)tetracarbonylmanganese (5a) and (1-methyl-3-formyl-ÎșO-indolyl-ÎșC2)tetracarbonylmanganese (5b). The unusually complicated crystal structure of 5b has been determined, the first for a cyclomanganated aryl aldehyde.
The preparations of a mitomycin-related pyrrolo-indole and related products by thermally promoted and oxidatively (Me3NO) initiated alkyne-coupling reactions of the previously known complex (1-acetyl-ÎșO-indolyl-ÎșC2)tetracarbonylmanganese (1) are reported for different alkynes and solvents. X-ray crystal structures are reported for the dimethyl acetylenedicarboxylate coupling product of 1 (dimethyl 1-methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate; 6a), and an unusually-cyclised triple insertion product 8 from the coupling of acetylene with 4, in which a cyclopentadiene moiety is η3-allyl-coordinated to Mn through only one double bond and an exocyclic carbon, but which rearranges on heating to an η5-cyclopentadienyl complex
Higher-order hbar corrections in the semiclassical quantization of chaotic billiards
In the periodic orbit quantization of physical systems, usually only the
leading-order hbar contribution to the density of states is considered.
Therefore, by construction, the eigenvalues following from semiclassical trace
formulae generally agree with the exact quantum ones only to lowest order of
hbar. In different theoretical work the trace formulae have been extended to
higher orders of hbar. The problem remains, however, how to actually calculate
eigenvalues from the extended trace formulae since, even with hbar corrections
included, the periodic orbit sums still do not converge in the physical domain.
For lowest-order semiclassical trace formulae the convergence problem can be
elegantly, and universally, circumvented by application of the technique of
harmonic inversion. In this paper we show how, for general scaling chaotic
systems, also higher-order hbar corrections to the Gutzwiller formula can be
included in the harmonic inversion scheme, and demonstrate that corrected
semiclassical eigenvalues can be calculated despite the convergence problem.
The method is applied to the open three-disk scattering system, as a prototype
of a chaotic system.Comment: 14 pages, 6 figures, accepted for publication in Eur. Phys. J.
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