Question in variational method (QM)

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SUMMARY

This discussion focuses on the variational method in quantum mechanics, specifically addressing Equation (9.133) from the book "Quantum Mechanics Concepts" by Nouredine Zettili. The user seeks clarification on the derivation of terms in the equation, particularly the transition from the first line to the second line. The solution involves calculating the expectation value of the Hamiltonian operator, leading to the integral expression involving the Gaussian function. The key missing term is identified as arising from the second derivative of the wave function.

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Safinaz
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Homework Statement



Hi, in this book " [Nouredine_Zettili]_Quantum_Mechanics_Concepts ", Eq. (9.133)

Homework Equations



I don't know how the second line

upload_2015-9-11_1-25-15.png


had come from the first line:
upload_2015-9-11_0-42-50.png

The Attempt at a Solution

I got only two terms such that:

$$ < \psi_0| H | \psi_0 > = A^2 \int^{+\infty}_{-\infty} \Big( - \frac{2\alpha^2 h^2}{m} e^{-2\alpha x^2} + \frac{1}{2} m \omega^2 x^2 e^{-2\alpha x^2} \Big) dx $$So what I missed ?
 

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Last edited:
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I fixed the images in your post.

The first derivative of ##e^{-\alpha x^2}## gives ##-2\alpha x e^{-\alpha x^2}##, the second derivative leads to ##(-2\alpha + 4\alpha^2 x^2) e^{-\alpha x^2}## and the second summand should give the missing term.
 
Yap ..
 

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