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Homework Help: Quantum Chemistry question

  1. Sep 30, 2006 #1
    There is an initial state Psi(x) =Ax(b/2 - x) when 0< x <b/2 and Psi(x) = 0 when b/2 < x <b

    I have to find the second lowest value possibly be obtained in a measurement of the energy.

    Should I treat this as a box with width b and possible energy states E=n^2*h^2/8mb^2 ? Or should I use the width b/2 ?

    Could someone please help me?
  2. jcsd
  3. Sep 30, 2006 #2


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    How are you going to incorporate the wave equations?
  4. Oct 1, 2006 #3
    Let me explain this problem better.
    What I have to do is calculate the propability that the measured energy from this system is E2
    O.K. So I have to find the Fourier coefficients, when I expand the initial state I mentioned above from 0 to b/2 in the eigenfunctions of the energy operator, or sqrt(2/b)*sin(n*pi*x/b). I know these eigenfunctions are derived from x=0 to x=b but Psi(x) =Ax(b/2 - x) is when 0< x <b/2
    I am doing this the correct way or am I way off?
    Last edited: Oct 1, 2006
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