What is the relationship between H, psi, and E in Quantum Mechanics?

xanmas
Messages
4
Reaction score
0

Homework Statement


I am currently doing undergraduate research and was assigned this as sort of an introduction. I am sure this is a very rudimentary problem and appreciate any help.

Basically, its your regular old H*psi = E*psi.

Well, knowing that H is psi(-D^2/Dx^2 + cosx + sin^2x = E*psi

and I want to prove that Ne^(lambda(1-cos)) is where E is equal to zero where N is the normalization constant and lambda is an arbitrary constant.

2. The attempt at a solution

The thing that I tried to do was divide by psi, and set E=0 to completely get rid of psi. I am not sure if I am allowed to do this but I did. This left me with

-D^2/Dx^2 + cosx + sin^2x = 0.

From there, I moved them to separate sides and doubly integrated. I got

ln|x| = cos^2(x)/4 - cos(x) +x^2/4

and exponentating I got

x = e^(Cos^2(x)/4 - cos(x) +x^2/4)

The problem is, without psi, I don't think that derivitave means anything and so I think I need to somehow keep the psi in there but I don't know what to do other than to divide out psi.

I would also rather a few hints instead of an explicit solution; I am sure that its just something that I am over looking and with a hint or two, I could do this.

I am very gracious of your help,

Thomas
 
Physics news on Phys.org
H operates on psi. So the equation is -psi(x)''+(cos(x)+sin^2(x))*psi(x)=0. And you don't have to solve it. Just substitute psi(x)=N*exp(lambda*(1-cos(x)). I think you'll find it works for only one choice of lambda.
 
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