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Problem understanding Green's function equality in Messiah QM II

  1. Sep 28, 2012 #1

    It's about green's function in the book Messiah - Quantum Mechanics II - Chapter 16.3.2
    (see http://books.google.de/books?id=OJ1...dq=messiah+quantenmechanik+kapitel+16.3&hl=de). The book actually is in german, but I guess that doesn't matter understanding the formulas.
    I don't understand the last equality between eq. (16.60) & (16.61). Why is there in the first term's nominator a 1 (instead of "z - H_o - lV")? Can somebody help me out?

  2. jcsd
  3. Sep 28, 2012 #2

    George Jones

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    Because the first term is

    \frac{1}{z-H_0} \left( z - H_0 -\lambda V \right) \frac{1}{z - H_0 -\lambda V} = \frac{1}{z-H_0}.
  4. Sep 28, 2012 #3
    oh dammit! :D

    thanks man!
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