Quick question about Kronecker delta function

Click For Summary
SUMMARY

The discussion focuses on the orthonormality of eigenfunctions in the infinite square well, specifically the sine functions represented by the equation ## \psi_n (x) = \sqrt{\dfrac{2}{a}} \sin \left( \dfrac{n \pi}{a} x \right) ##. It is established that the integral ## \int \psi_m (x) ^* \psi_n (x) dx = \delta_{mn} ## confirms the orthogonality of these states. Furthermore, it is confirmed that cosine functions also maintain orthonormality, with a recommendation to prove this using the trigonometric identity for cosines.

PREREQUISITES
  • Understanding of quantum mechanics concepts, particularly the infinite square well model.
  • Familiarity with eigenfunctions and their properties in quantum systems.
  • Knowledge of orthonormality and inner product integrals.
  • Basic proficiency in trigonometric identities and integration techniques.
NEXT STEPS
  • Study the properties of eigenfunctions in quantum mechanics, focusing on the infinite square well.
  • Learn about the orthonormality of cosine functions in quantum systems.
  • Explore trigonometric identities and their applications in integrals.
  • Investigate the implications of orthogonality in quantum state measurements.
USEFUL FOR

Students and professionals in physics, particularly those studying quantum mechanics, as well as educators looking to enhance their understanding of eigenfunctions and orthonormality in quantum systems.

Cogswell
Messages
54
Reaction score
0
So in the infinite square well, the eigenfunctions are ## \psi_n (x) = \sqrt{\dfrac{2}{a}} \sin \left( \dfrac{n \pi}{a} x \right) ##

Each state is orthogonal to each other, and so ## \displaystyle \int \psi_m (x) ^* \psi_n (x) dx = \delta_{mn} ##

Does this also hold if they were cosines?
 
Physics news on Phys.org
Yes, the cosines are also orthonormal.
 
You should be able to easily prove this yourself. Just use the trig identity for cos A cos B, and do the integral.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
9K
  • · Replies 26 ·
Replies
26
Views
5K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 18 ·
Replies
18
Views
5K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 59 ·
2
Replies
59
Views
6K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 3 ·
Replies
3
Views
3K