How are these eigenfunctions obvious (by inspection)?

  • Thread starter Thread starter ihatelolcats
  • Start date Start date
  • Tags Tags
    Eigenfunctions
Click For Summary
SUMMARY

The discussion focuses on the identification of eigenfunctions in quantum mechanics, specifically the functions psi_211 and psi_21-1, which are confirmed as eigenfunctions due to their zero values. The presence of two non-zero off-diagonal elements in the associated matrix indicates non-zero eigenvalues, leading to the conclusion that the eigenfunctions are linear combinations of the states φ_{200} and φ_{210}. The equality of the off-diagonal elements results in equal coefficients for these states, ensuring the normalization of the eigenfunctions.

PREREQUISITES
  • Understanding of quantum mechanics principles, particularly eigenfunctions and eigenvalues.
  • Familiarity with matrix representation of quantum states.
  • Knowledge of linear combinations and normalization in the context of quantum states.
  • Experience with solving matrix eigenvalue problems.
NEXT STEPS
  • Study the properties of eigenvalues and eigenfunctions in quantum mechanics.
  • Learn about matrix diagonalization techniques in quantum systems.
  • Explore the implications of off-diagonal elements in quantum mechanical matrices.
  • Investigate normalization conditions for quantum states and their significance.
USEFUL FOR

Students and professionals in physics, particularly those specializing in quantum mechanics, as well as researchers working on eigenvalue problems in quantum systems.

ihatelolcats
Messages
13
Reaction score
0
[PLAIN]http://img251.imageshack.us/img251/1050/quantume.png

taken from http://quantummechanics.ucsd.edu/ph130a/130_notes/node338.html

I see how psi_211 and psi_21-1 are eigenfunctions, because they are just 0.
I don't see how they got the other two (+/-).

Thanks in advance
 
Last edited by a moderator:
Physics news on Phys.org
Well, this is the way I would inspect the equations:

You have two non-zero off diagonal elements in your matrix. So, you know you are going to have some non zero eigenvalues.

The non zero values fall in the positions of the matrix that connect \phi_{200} and \phi_{210}. Thus, we know that (from previously solving a lot of matrix eigenvalue problems and noticing patterns) the eigenfunctions will be linear combinations of \phi_{200} and \phi_{210}.

The off diagonal elements are equal, so the coefficients of \phi_{200} and \phi_{210} will be equal. We need to have normalize eigenfunctions so, we get the linear combinations given above.
 
Last edited:

Similar threads

  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
1
Views
2K
  • · Replies 11 ·
Replies
11
Views
6K
Replies
8
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
Replies
4
Views
4K
Replies
4
Views
3K
  • · Replies 9 ·
Replies
9
Views
7K