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Homework Help: Kittel page 174

  1. Feb 29, 2008 #1
    1. The problem statement, all variables and given/known data
    This question refers to Kittel's solid-state physics book.

    On this page, in the section about the "Kronig-Penney Model in Reciprocal Space", I do not understand why the sum over s is from 0 to 1/a. What if a is 2?

    Also, how do they know that "the boundary conditions are periodic over a ring of unit length"?

    2. Relevant equations

    3. The attempt at a solution
    Last edited: Feb 29, 2008
  2. jcsd
  3. Mar 1, 2008 #2


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    Science Advisor
    Homework Helper

    Then you only sum over zero.
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