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The effect of vibrational anharmonicity on the thermal scattering of X-rays from crystals is calculated for temperatures above the Debye temperature. A revised method of interpreting the experimental data is suggested. The (temperature dependent) dispersion curves (frequency vs. wave-vector) for small wave-vectors are determined by the isothermal rather than the adiabatic elastic constants. A procedure is outlined to extrapolate from the (temperature dependent) scattering data the (temperature independent) dispersion curves which correspond to the harmonic approximation. 相似文献
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Harro Hahn 《Zeitschrift für Physik A Hadrons and Nuclei》1961,165(5):569-600
Work already published under the above topic by W.Ludwig and the author was limited to crystal temperatures above the Debye temperature, as it treated the lattice vibrations by classical statistics. In this paper, a complete quantum-statistical treatment is presented. The essential features of the high temperature results remain unchanged: New, temperature dependent dispersion curves may be introduced which, for long waves, are determined by theisothermal elastic constants. 相似文献
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