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Homework Help: Electrostatic Potential Energy of an ion

  1. Mar 17, 2013 #1
    Working from Krane's Modern Physics 11.5

    Calculate the first 3 contributions to the electrostatic potential energy of an ion in the CsCl lattice.

    I believe the formula I'm supposed to use is

    Just from looking in the chapter I can see this is a bcc type lattice with an [itex]\alpha[/itex] of 1.7627, but I'm not sure how they're getting the answer in the back of the book which is;
    U_{c}\,=\,-\frac{e^{2}}{4\pi\epsilon_{0}R}\left(8-\frac{6}{2/\sqrt{3}} + \frac{24}{\sqrt{11/3}}\right)
    There's an example in the book showing the same procedure for an fcc lattice (NaCl) and that converging term is,
    but it doesn't derive it, so I'm not really sure how they get it.

    Just looking for a few pointers, thanks.
  2. jcsd
  3. Mar 17, 2013 #2
    Figured it out.
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