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The Einstein solid is a model of a solid based on two assumptions: * Each atom in the lattice is an independent 3D quantum harmonic oscillator * All atoms oscillate with the same frequency (contrast with the Debye model) While the assumption that a solid has independent oscillations is very accurate, these oscillations are sound waves or phonons, collective modes involving many atoms. In the Einstein model, each atom oscillates independently. Einstein was aware that getting the frequency of the actual oscillations would be difficult, but he nevertheless proposed this theory because it was a particularly clear demonstration that quantum mechanics could solve the specific heat problem in classical mechanics. == Historical impact == The original theory proposed by Einstein in 1907 has great historical relevance. The heat capacity of solids as predicted by the empirical Dulong-Petit law was required by classical mechanics, the specific heat of solids should be independent of temperature. But experiments at low temperatures showed that the heat capacity changes, going to zero at absolute zero. As the temperature goes up, the specific heat goes up until it approaches the Dulong and Petit prediction at high temperature. By employing Planck's quantization assumption, Einstein's theory accounted for the observed experimental trend for the first time. Together with the photoelectric effect, this became one of the most important pieces of evidence for the need of quantization. Einstein used the levels of the quantum mechanical oscillator many years before the advent of modern quantum mechanics. In Einstein's model, the specific heat approaches zero exponentially fast at low temperatures. This is because all the oscillations have one common frequency. The correct behavior is found by quantizing the normal modes of the solid in the same way that Einstein suggested. Then the frequencies of the waves are not all the same, and the specific heat goes to zero as a power law, which matches experiment. This modification is called the Debye Model, which appeared in 1912. When Walther Nernst learned of Einstein's 1907 paper on specific heat,〔Annalen der Physik (ser. 4), 22, 180–190, 800 link and correction〕 he was so excited that he traveled all the way from Berlin to Zurich to meet with him.〔''Einstein and the Quantum'', A. Douglas Stone, Princeton University Press, 2013, p. 146.〕〔http://press.princeton.edu/titles/10068.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Einstein solid」の詳細全文を読む スポンサード リンク
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