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921.
The techniques of quantum field theory are used to investigate the thermodynamic ion displacement correlation function—or Green's function of the phonon field—in a crystal and especially in a metal. The structure of thermodynamic Green's functions is outlined and the method for solving for them at finite temperature is fully discussed.The analytic structure of the phonon Green's function is then considered. This function is shown to be bounded and invertible everywhere off the real axis; a spectral form is derived for its inverse. The symmetries imposed by the point group of the crystal are then discussed.Assuming small ionic oscillations, we find the inverse of the phonon Green's function as a linear function of the electronic contribution to the dielectric response function of the metal. This dielectric function is shown to be simply related to the longitudinal part of the conductivity tensor that gives the response of the electrons to the effective electric field in the metal. The assumption of translational invariance then leads to an explicit expression for the phonon Green's function in terms of this conductivity.The deformations in the lattice induced by an arbitrarily time varying external force are calculated in terms of the retarded phonon Green's function. In the static long wavelength limit the phonon Green's function yields the macroscopic elastic constants of the crystal. Their relation to the conductivity is exhibited, and several elastic constants are estimated. We also see that the complete phonon spectrum and the lifetimes of the phonon states may be calculated from this Green's function. A relation between the long wavelength acoustic attenuation in metals and the de conductivity is derived, which is in good agreement with recent experiments. Furthermore, the ions in a metal are shown to have a high-frequency oscillation along with the electrons, at essentially the electron plasma frequency. 相似文献
922.
F.T. Dao D. Gordon J. Lach E. Malamud J. Schivell T. Meyer R. Poster P.E. Schlein W.E. Slater 《Physics letters. [Part B]》1973,45(4):402-404
We have studied the properties of the inclusive pp → pX reation at . Protons of momentum or less are measured and identified by their ionization. We investigate the multiplicity distribution associated with those events having a small four-momentum transfer to the target proton. Under the assumption that this selection enhances or isolates the diffractive component of the interaction, we discuss the properties of the diffractive and nondiffractive components. 相似文献
923.
924.
925.
Gordon C. K. Yeh 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1964,15(3):237-252
Zusammenfassung Ein sphärischer Hohlraum in einem unendlichen homogenen und isotropen elastischen Medium wird von einer ebenen Druckstosswelle überstrichen, deren Front sich gleichförmig fortbewegt. Das durch Ablenkung am Hohlraum erzeugte Verschiebungs- und spannungsfeld wird mittels einer Integraltransformation bestimmt. Insbesondere wird die starre Teilbewegung der Begrenzung des Hohlraums ermittelt. Das Problem wird für eine einstufige Druckwelle gelöst. Die Ergebnisse lassen sich als Einflussgrössen betrachten, mit denen sich die Duhamel-Integrale für allgemeinere Druckwellen berechnen lassen.
This work was performed under Contract No. AF 29(601)-5132 (Project No. 1080, Task No. 108007) for Air Force Special Weapons Center, Kirtland Air Force Base, New Mexico, USA. 相似文献
This work was performed under Contract No. AF 29(601)-5132 (Project No. 1080, Task No. 108007) for Air Force Special Weapons Center, Kirtland Air Force Base, New Mexico, USA. 相似文献
926.
Yehoram Gordon 《Israel Journal of Mathematics》1966,4(3):177-188
GivenF(z),f
1(z), ..,f
n(z) defined on a finite point setE, and givenB — the set of generalised polynomials Σ
k
=1/n
a
kfk(z) — the definition of a juxtapolynomial is extended in the following manner: for a fixedλ(0<λ≦1),f(z) εB is called a generalizedλ-weak juxtapolynomial toF(z) onE if and only if there exists nog(z) εB for whichg(z)=F(z) wheneverf(z)=F(z) and |g(z)−F(z) |<λ|f(z)−F(z)| wheneverf(z)≠F(z). The properties of suchf(z) are investigated with particular attention given to the real case.
This note is an extension of a part of the author’s M.Sc. Thesis under the supervision of Prof. B. Grünbaum to whom the author
wishes to express his sincerest appreciation. The author also wishes to thank Dr. J. Lindenstrauss for his valuable remarks
in the preparation of this paper. 相似文献
927.
This paper deals with the following problem posed by Professor T. S. Motzkin: Suppose M is a given set of positive integers. How dense can a set S of positive integers be, if no two elements of S are allowed to differ by an element of M? The problem is solved for |M| ? 2, and some partial results are obtained in the general case. 相似文献
928.
Functionally-substituted carbon nucleophiles undergo addition to arenes coordinated to positive iron, but nitrogen and oxygen nucleophiles abstract α protons from iron-coordinated methylated arenes. 相似文献
929.
930.