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

Homework Help: Kittel nearly free electron model

  1. Mar 24, 2008 #1
    1. The problem statement, all variables and given/known data
    This question refers to Kittel's solid-state physics book.

    I just do not understand the 1D example on pages 164-65. So, I understand everything until the line "The wavefunctions at [itex]k = \pm \pi/a[/itex] are not the traveling waves [itex]\exp(i\pi x/a)[/itex] or [itex]\exp(i\pi x/a)[/itex] of free electrons."

    Kittel tries to explain, but I just don't understand. Is he saying that they will just bounce back and forth between k = pi/a and k = -pi/a by Bragg reflection? How does he know that!?!?!? PLEASE HELP!!


    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Mar 24, 2008
  2. jcsd
  3. Mar 24, 2008 #2
    I'm afraid I don't understand what you don't understand. Isn't he just stating that electrons in a lattice aren't free?
     
  4. Mar 24, 2008 #3
    He is saying that it is only true for wavefunctions at [itex]k = \pm \pi/a[/itex].

    genneth, do you have the book? If not then it will be hard to answer this question since I really don't understand like half a page after that and a figure on the previous page.

    But thanks for your effort.
     
  5. Mar 25, 2008 #4
    anyone ?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook