Trial function and Eigenfunction....

Ronf
Messages
2
Reaction score
0

Homework Statement


Hello, I just started to study QM, I just have a general question, how to know if a trial function is not an eigenfunction of a hamiltonian (that has the lowest value in a graph) ? - Thanks and sorry for the stupid question.

Homework Equations

The Attempt at a Solution


I have an idea, but I am not sure if it is right. Is the trial function a eigenfuction of a hamiltonian, if it gives a value (lowest) which is very close to the ground-state energy? [/B]
 

Attachments

  • Screenshot_7.png
    Screenshot_7.png
    3.4 KB · Views: 407
Last edited:
Physics news on Phys.org
Ronf said:
how to know if a trial function is not an eigenfunction of a hamiltonian (that has the lowest value in a graph) ?
It is not when the corresponding expectation value of energy does not match any of the eignvalues of the Hamiltonian.
Ronf said:
Is the trial function a eigenfuction of a hamiltonian, if it gives a value (lowest) which is very close to the ground-state energy?
Again, if this value is not exactly the same as one of the Hamiltonian's eigenvalues, then the tried function is not an eigenfunction.
 
  • Like
Likes Ronf
Thank you man, I really appreciate your help, much love to you. :smile:
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top