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The wave function at the border of Wigner-Seitz cell

  1. May 8, 2013 #1
    In the cellular method of calculating the band structure:
    Why we have to take zero the normal derivative of the wave function at the Wigner-Seitz cell's border?
  2. jcsd
  3. May 8, 2013 #2
    Because of symmetry. At the faces of the Wigner-Seitz cells there is a mirror symmetry, and if the wavefunction has a non-zero derivative at that point (normal to the face) that would violate the requirement of the Schrodinger equation that the wavefunction be twice-differentiable in all space.
  4. May 9, 2013 #3


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    Also take in mind that this only holds for the states with k=0.
  5. May 9, 2013 #4
    I thank both of you daveyrocket and DrDu.
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