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What are Jacobi coordinates, and why are they useful?

  1. Jun 10, 2009 #1
    What are "Jacobi coordinates," and why are they useful?

    I am working on a quantum chemistry problem involving triatomic molecules. My advisor keeps talking about "Jacobi coordinates" and how they're a calculational convenience when it comes time to write out the Hamiltonian. Can someone describe them to me, and why they make life easier? I can't seem to find a good resource for this on the Web...
     
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  3. Jun 11, 2009 #2

    clem

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    Re: What are "Jacobi coordinates," and why are they useful?

    Jacobi coordinates are coordinates for three bodies of equal mass, using the cm of two of them. The coordinates I like to use are
    R=(r1+r2+r3)/3
    r=(r1-r2)/2
    rho=(2/3)[r3-(r1+r2)/2].
    The more common Jacobi coordinates divide by square roots to make equations more symmetric, but they get more complicated in practice.
    If one of the bodies has a different mass, then masses have to enter.
     
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