A Theory of Phonon-Like Excitations in Non-Crystalline Solids and Liquids

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概要

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• Elementary excitations associated with atomic motion in non-crystalline solids and liquids are studied with particular attention paid to the dependence of their dispersion on local order. In doing this, an attempt is made to obtain an exact formal expression for an effective dynamical matrix giving the eigenfrequencies of phonons in a non-crystalline solid in terms of "effective pair-correlation functions". A brief remark is also given on the moment method and sum rules for the dynamic structure factor to study high-frequency collective motion in liquids. It is suggested that under certain restrictions the phonon-roton-like behavior of excitations as observed in liquid helium is likely to exist in almost all types of structure or topological disorder systems (amorphous and glassy solids, liquids, etc.). To substantiate this, a model one-dimensional system is chosen to show how a phonon dispersion curve in a crystal lattice is modified, as the partial disorder characterizing a structure disorder system is introduced. Such a local disorder is shown to give rise to a frequency gap which decreases with increasing local order and eventually vanishes in the case of complete order. This result is also in qualitative agreement with the pressure- and the temperature-dependence of the roton minimum energy in liquid helium. Simple numerical calculations are made to compare the obtained results with experiments for collective motion in liquid argon and also in liquid helium. Fairly good agreement is obtained.

• 理論物理学刊行会の論文
• 1972-03-25

著者

• Goda Masaki

  Department Of Materials Science And Technology Faculty Of Engineering Institute Of Natural Science N

• Takeno Shozo

  Research Institute For Fundamental Physics Kyoto University

• Takeno Shozo

  Research Institute For Fundamental Physics Kyoto University : Department Of Nuclear Engineering Kyot

• Goda Masaki

  Department Of Physics Hokkaido University

• TAKENO Shozo

  Research Institute for Fundamental Physics, Kyoto University : Department of Nuclear Engineering, Kyoto University

• GODA Masaki

  Department of Physics, Hokkaido University

関連論文

• Phonon-Like Excitations in Liquid Helium
• Frequency Spectrum and Low-Temperature Specific Heat of Noncrystalline Solids
• Localization of Long-Wavelength Acoustic Phonons in a Disordered Anomalous Soft Solid with Parabolic Dispersion Relation
• A Solution of a Dyson Equation in Many-Impurity Problems in Solids : An Extended Impurity Potential
• A Theory of Phonon-Like Excitations in Non-Crystalline Solids and Liquids
• A Theory of Multiple Scattering of Waves in a Random Medium
• A Theory of the Lattice Vibrations of Anharmonic Solids
• A Low-Lying Magnon Resonant Mode in an Impure Heisenberg Ferromagnet
• A Theory of Phonons in Amorphous Solids and Its Implications to Collective Motion in Simple Liquids
• Theory of Impurity-Induced Infrared Absorption in Alkali Halide Crystals
• The Inelastic Scattering of an Electron by a Nonmagnetic Impurity in a Crystal

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