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I Thermal expansion in harmonic potential

  1. Sep 10, 2016 #1


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    It is generally said that thermal expansion is a process determinated by the anharmonic terms in the potential of a crystalline solid. However, in the Course of Theoretical Physics by Landau Lifshitz, Statistical Physics part 1, paragraph 67, a form for the coefficient of thermal expansion is derived from the free energy of a harmonic solid. How's that possible if in an harmonic potential no thermal expansion should be present? Thanks in advance!
  2. jcsd
  3. Sep 13, 2016 #2
    Ashby suggests that the atomic bond exhibits linear elasticity for only small relative displacement of atoms. I presume that this is the range for which the expansion coefficient is valid.
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