Non relativistic continuum wave functions for two coulomb centres

We give the continuum wave function solutions to the Schrödinger equation for an electron moving field of two point nuclei, as an expansion in terms of one centre Coulomb wave functions in a prolate elliptical coordinate system. These solutions may be chosen to have a convenient asymptotic behaviour, and tend to the conventional solutions of the Helmholtz equation in the limit that the nuclear charge goes to zero. In symmetric systems, where both nuclei have the same charge the angular wave functions are found to be identical with those occurring in the free case, and the expansion coefficients for the corresponding radial solutions are given for selected values of electron energy and nuclear separation.[/p]     

X-ray diffraction and morphology of crystalline,hard, elastic materials

Summary X-ray diffraction and electron microscopic results on several crystalline polymers which demonstrate elastic properties (polypropylene, Celcon^®, poly-4-methyl-pentene) are reported. Photographic small angle X-ray diffraction techniques provided considerable qualitative information, concerning the morphological features of these elastic materials both as extruded, annealed and during extension. Lamellar thickness, thickness distribution and perfection of lamellae could be estimated. Lateral order features and orientation of the lamellar structures were obtainable from the sharpness and length of the equatorial wide angle diffraction arcs. Electron microscopic results essentially confirm the morphological features postulated on the basis of the X-ray results. These morphological features are discussed in terms of a general structural model which appears consistent with the mechanical properties of these materials.

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Zusammenfassung Röntgenbeugung und elektronenmikroskopische Daten von einigen kristallinen Polymerprodukten mit elastischen Eigenschaften (Polypropylen, Celcon, Poly-4-methylpenten) werden berichtet. Die photographische Röntgen-Kleinwinkelmethode liefert wichtige qualitative Messungen der morphologischen Struktur dieser elastischen Materialien in den Zuständen sowohl wie hergestellt als auch nach Tempern und während des Dehnungsprozesses. Die Dicke der Lamellen, ihre Dikkenverteilung und die Güte der Lamellen konnten abgeschätzt werden. Die laterale Ordnung und die Orientierung der Lamellen kann aus Weitwinkelbeugungsdaten abgeleitet werden. Die Elektronenmikroskopie bestätigt die Morphologie, die aus Röntgendaten folgt. Ein allgemeines Strukturmodel dieser Morphologie, das im Einklang mit den mechanischen Eigenschaften dieser Produkte steht, wird diskutiert.

     

Untersuchungen zum Dehnungsverhalten von Polybutylenterephthalat (PBT)-Folien

Zusammenfassung Anhand von Röntgenuntersuchungen wurden dehnungsund belastungsabhängige Veränderungen der PBT-Ketten-konformation untersucht. Die Faseridentitätsperiode (FIP) des PBT vergrößert sich beim Dehnen oder Belasten diskontinuierlich, der Blättchenebenenabstand verkleinert sich dagegen kontinuierlich. Die auftretenden Gitterstörungen, deren Modell diskutiert wird, werden durch Veränderungen der Kettenkonformation hervorgerufen.Die von den anderen Autoren gefundene-Struktur des PBT wurde nur bei hoch gedehnten ( = 18%) PBT-Proben nachgewiesen, kann aber zur Erklärung der Umwandlung der PBT-Kettenkonformation nicht herangezogen werden.

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Summary Stress and strain induced changes in the chain conformation of polybutylene terephthalate (PBT) were determined by X-ray measurements.The fibre identity period (FIP) increases discontinuously with stress or strain, whereas the (100) Bragg spacing (Blättchenebenenabstand) decreases continuously.Lattice distortions are due to these changes in the PBT chain conformation. A model of these lattice distortions is presented and discussed.The so-called-structure of PBT given by other authors exists only in the case of highly strained ( 18% PBT fibres.The changes in the PBT chain conformation cannot be attributed solely to the existence of the-structure.

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Mit 12 Abbildungen und 2 Tabellen     

Frequency-dependent linear response of superconducting systems

We present a density functional scheme for calculating the frequency-dependent linear response of superconductors. The central result is a set of integral equations determining the linear response of the normal and anomalous densities to external perturbations. Analytic solutions of these integral equations are obtained for homogeneous systems with separable effective interactions. For inhomogeneous superconductors, the formalism leads to a scheme for calculating the critical temperature without explicitly solving the gap equation. © 1995 John Wiley & Sons, Inc.     

[(C6H5)3P]2Ni(Me3Si?CC?SiMe3). Darstellung,Eigenschaften und Struktur des ersten stabilen Nickel(0)-Komplexes von Bis-trimethylsilylacetylen

[(C₆H₅)₃P]₂Ni(Me₃Si? C?C? SiMe₃). Preparation, Properties, and Structure of the First Stable Nickel(0) Complex with Bis(trimethylsilyl)acetylene The title compound is the first example of a nickel(0) complex with bis(trimethylsilyl)acetylene and obtained from (ph₃P)₂Ni(C₂H₄) and bis(trimethylsilyl)acetylene in tetrahydrofuran. The complex is characterized by some reactions, the i.r. spectrum and by a structural analysis with the aid of X-ray diffraction data. (ph₃P)₂Ni(Me₃Si? C?C? SiMe₃) crystallizes monoclinic in the space group C2/c with four formula units per unit cell (2468 observed, independent reflexions, R = 0.038). The cell dimensions are a = 20.927, b = 13.812, c = 14.238 Å, α = γ = 90°, β = 91.02°. The molecules are monomer in crystalls. The molecule is planar with ligands arranged trigonally about the central atome but distorted to the tetrahedral complex.     

Relations between subclasses of greedoids

In previous papers many different classes and constructions of greedoids have been defined and studied. This paper documents inclusion relations among all subclasses of greedoids which are known so far. It will be shown that all inclusion relations are proper and that all but one subclasses of interval greedoids are distinct.

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Zusammenfassung In früheren Arbeiten wurden viele verschiedene Klassen und Konstruktionen für Greedoide eingeführt und studiert. In dieser Arbeit werden alle bekannten Inklusionsbeziehungen zwischen Unterklassen von Greedoiden dokumentiert. Es wird gezeigt, daß alle Inklusionsbeziehungen echt und alle Unterklassen mit einer Ausnahme tatsächlich verschieden sind.

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Supported by the joint research project Algorithmic Aspects of Combinatorial Optimization of the Hungarian Academy of Sciences (Magyar Tudományos Akadémia) and the German Research Association (Deutsche Forschungsgemeinschaft, SFB 21). Part of this research was done while the first author was visiting the Department of Combinatorics and Optimization, University of Waterloo.     

Structure investigations on the hot-working behaviour of steel

Structure changes occurring in hot-deformation of the austenite of steel, the - phase transformation of which takes place above room temperature, cannot directly be studied with quenched specimens. However, within certain limits a microstructure characterization is possible by means of investigation of carefully selected model alloys and/or by analysis of the microstructure inheritance associated with a martensitic - transition of the hot-worked austenite. Application of both procedures is demonstrated with results which were obtained in investigations of the hot-working behaviour of low-alloy spring steel and an Fe-Ni-C model alloy.     

Effect of hydrostatic pressure on the static susceptibility of the spin-glass systems Ag:Mn,Au:Mn,Cu:Mn and Au:Fe

Previous studies of the magnetic susceptibility of a Ag-3 at.% Mn spin-glass under high pressure are extended to include the systems Au-3at.% Mn, Cu-3at.% Mn and Au-3at.% Fe. In all four alloys the spin-glass freezing temperatureT ₀ increases with pressure, yielding the volume dependences lnT ₀/ lnV=–3.6±0.4, –4.1±0.6, –2.1±0.4 and –1.64±0.25, respectively. These results give information about the nature of the interaction mechanisms responsible for the spin-glass freezing phenomena. The pressure dependence of the Curie temperature of ferromagnetic Au-20at.% Fe was also studied.Dedicated to B. Mühlschlegel on the occasion of his 60th birthday     

Triphenylphosphan-Nickel(0)-Komplexe mit Isocyanid-Liganden — [(RNC)nNi(PPh3)4–n] (n = 1–3)

Triphenylphosphane Nickel(0) Complexes with Isocyanide Ligands — [(RNC)_nNi(PPh₃)_4–n] (n = 1–3) Synthesis and properties of the isocyanide triphenylphosphane nickel(0) complexes [(RNC)Ni(PPh₃)₃], [(RNC)₂Ni(PPh₃)₂] and [(RNC)₃Ni(PPh₃)] (R = ^tBu, Cy, PhCH₂, p-TosCH₂) are described. I.r. and ³¹P n.m.r. spectra were recorded and the X-ray crystal structure of [(PhCH₂NC)₂Ni(PPh₃)₂] was determined.