Derivation of momentum expectancy

  • Thread starter A_B
  • Start date
  • #1
A_B
93
1
Hi,

I'm working through Griffiths' Introduction to QM, In the derivation for the expectation value of momentum, he uses that
[tex]\left( x \left. \left( \Psi^* \frac{\partial\Psi}{\partial x} - \frac{\partial \Psi^*}{\partial x}\Psi \right) \right) \right|_{-\infty}^{+\infty} = 0[/tex]

Why is this so? It's easy to see that this is zero if the x weren't there, but I can't figure out why the limits are zero with the x in.

Thanks,
A_B
 
Last edited:

Answers and Replies

  • #2
322
0
since you said that it's easy to see that this is zeero if the x weren't there, wouldn't that mean by your reasoning that everything inside the brackets would equal zero.
 
  • #3
A_B
93
1
I'm sorry, the x is included in the evaluation, I edited the first post to make that clear, thanks.
 

Related Threads on Derivation of momentum expectancy

  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
0
Views
4K
Replies
6
Views
1K
Replies
30
Views
1K
Replies
4
Views
887
Replies
1
Views
2K
Replies
1
Views
2K
  • Last Post
Replies
2
Views
916
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
7K
Top