Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

High symmetry points and lines in Brillioun Zone

  1. Oct 1, 2013 #1


    User Avatar


    I've seen pictures like this one: http://www.lcst-cn.org/Solid%20State%20Physics/Ch25.files/image002.gif [Broken]
    Is there any good explanation somewhere on this subject?

    I'm using Kittel's book but there's nothing in there on this.
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Oct 1, 2013 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    What explanation exactly do you need? An explanation on what a Brillouin zone is?

  4. Oct 1, 2013 #3


    User Avatar

    I know that a Brillioun Zone is a Wigner Seitz cell in k-space, but what are the symmetry points and lines?

    How are these used and what physical significance do they have?

    How are they chosen?

    I've read the first 6 chapters in Kittel. I don't think we're required to know this in the course I'm taking, just asking out of curiosity. :)
    Last edited: Oct 1, 2013
  5. Oct 1, 2013 #4
    You need to study a little group theory as it applies to crystallographic symmetries. It is surprisingly easy to understand. I leaned it from the book by Micheal Tinkham "Group Theory in Quantum Mechanics". Basically, the geometric structure of the Wigner Seitz cell is subsumed to an irreducible representation of the geometry by the symmetry group operators of rotation, reflection, and inversion.

    This technique is fundamental to the interpretation of almost all solid state spectroscopic experiments (i.e. x-ray diffraction, EPR etc).
    Last edited: Oct 1, 2013
  6. Oct 1, 2013 #5


    User Avatar

    I have been thinking about buying that book actually, it seems quite interesting. How much mathematics and QM is required to understand it?

    I have Ashcroft as well. There's a section on point groups and such but the notation is different, is this the same thing as high symmetry points? I didn't bother reading it yet as the subject seemed to be different. I bought the book as a supplement but haven't been using it that much.

    My understanding is only basic so far. I know some basic QM and I'm studying Kittel.
  7. Oct 1, 2013 #6
    The first four chapters or so of Tinkham are related to crystallographic symmetry groups. The math is not hard at all. If you can do the problems in Kittel, you can work through Tinkham. I suggest you read the first few chapters and try to work the problems. The time spent studying group theory will be enormously beneficial to your understanding of solid state physics.
  8. Oct 2, 2013 #7
    Look at the point group of the crystal.

    Then pick a point within the BZ, e.g. one of the special points (Gamma, X, L, K, U, W) or along one of the special lines (Sigma, Lambda, Delta), or any other point.

    Then figure out which of the symmetry operations of the point group project that point onto itself (or itself+reciprocal lattice vector).

    What do you get?
  9. Oct 2, 2013 #8


    User Avatar
    Science Advisor

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook