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Homework Help: QM and van der Waals forces

  1. Sep 2, 2009 #1
    1. The problem statement, all variables and given/known data
    Hi all

    Please take a look at this link: http://books.google.dk/books?id=bA9...e is an attractive potential between"&f=false

    I have a question for the above-mentioned case with van der Waals interaction: In my QM-book (Griffiths, problem 6.31), we look at a system of two neutral atoms a distance R apart. Treating the Coulomb-interaction as a perturbation, we have the following values:

    Eunperturbed = [itex]\hbar \omega_0[/itex]
    Eperturbation, total = Eunperturbed + Efirst order

    Thus we have

    Eperturbed, total-Eunperturbed = Efirst order < 0.

    Now the author concludes that this implies an attractive potential between the atoms, and this is called the van der Waals interaction. I don't understand why we are able to conclude that?
    Last edited: Sep 2, 2009
  2. jcsd
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