# Recent content by cyberdeathreaper

1. ### 2D Harmonic Oscillator

Corrected the problems you pointed out Gokul. Other than those minor issues though, my solution proposed in #10 is correct then?
2. ### 2D Harmonic Oscillator

I see - so technically the eigenvalues are: \hbar w \left( n + m + 1 \right) and the eigenfunctions are: \Psi_{nm} = C_{nm} (a_+^n \psi_0(x)) (b_+^m \psi_0(y)) with: C_{nm} = A_n A_m right?
3. ### 2D Harmonic Oscillator

with n = 0,1,2...... correct?
4. ### Infinite Potential Well

Okay, I think I've got it. Does this look correct? ANS: I'm looking for first-order correction to the nth eigenvalue - so I need to solve this: E_n^1 = \left< \psi_n^0 | H' | \psi_n^0 \right> Where \psi_n^0 (x) = \sqrt{ \frac{2}{a} } sin \left( \frac{n \pi x}{a} \right) and H'...
5. ### 2D Harmonic Oscillator

Okay, I think I've got it then. Is this correct: \hat{H} = \frac{ (p_x)^2 }{2m} + \frac{ (p_y)^2 }{2m} + \frac{mw^2}{2} \left( x^2 + y^2 \right) Which is broken up into components: \hat{H} = \hat{H_x} + \hat{H_y} Noting the 1-D harmonic oscillator gives: E_x = \hbar w \left( n_x...
6. ### 2D Harmonic Oscillator

We have covered the 1D harmonic oscillator, but we haven't seen any other higher dimensional setups yet. We have also used the seperation of variables so far, just not in regards to higher-dimensions. Just as a general question - once the equation is broken down into two 1D equations, how...
7. ### 2D Harmonic Oscillator

This might be another problem that our class hasn't covered material to answer yet - but I want to be sure. The question is the following: Find the eigenfunctions and eigenvalues of a two-dimensional isotropic harmonic oscillator. Again, I need help simply starting.
8. ### Infinite Potential Well

Sorry for all the questions - I tend to save them till I'm done with assignments: Here's the question: Consider a particle of mass 'm' in a one-dimensional infinite potential well of width 'a' V (x) = \left\{\begin{array}{c} 0 \ \ \ if \ \ \ 0 \leq x \leq a \\ \infty \ \ \ otherwise...
9. ### Dirac delta function

Thanks, I knew it was related to that. I just wasn't sure if it applied for functions of more than one variable or not.
10. ### Dirac delta function

Can someone help me understand the transition between these two steps? <x> = \iint \Phi^* (p',t) \delta (p - p') \left( - \frac{\hbar}{i} \frac{\partial}{\partial p} \Phi (p,t) \right) dp' dp = <x> = \int \Phi^* (p,t) \left( - \frac{\hbar}{i} \frac{\partial}{\partial p} \Phi (p,t)...
11. ### Choosing a programming language - physics

Thanks for the recommendations. I didn't realize C++ could be used in conjuction with Matlab/Mathematica - do you know of any sources out there that describe how to do it?
12. ### Eigenfunctions and eigenvalues

Nevermind, I got it now - didn't realize the relation between 1 and e^(i2n(pi)).... A e^{\sqrt{q} \phi} = A e^{\sqrt{q} \left( \phi + 2 \pi \right)} e^{\sqrt{q} \phi} = e^{\sqrt{q} \phi} e^{\sqrt{q} 2 \pi} 1 = e^{\sqrt{q} 2 \pi} e^{i 2 n \pi} = e^{\sqrt{q} 2 \pi} i 2 n...
13. ### Choosing a programming language - physics

If I'm going to attempt creating computer programs for simulating theories as complicated as string theory, what language should I be looking at? I have some experience with C++, but if I'm going to devote a large part of my free time to learning a language, I'd like to learn something that...
14. ### Eigenfunctions and eigenvalues

An additional question, somewhat related: When determining the eigenvalues, the problem indicates that f (\phi + 2\pi) = f (\phi) Given the answer already shown, why would this periodic function require: 2 \pi \sqrt{q} = 2 n \pi i
15. ### Eigenfunctions and eigenvalues

thanks - knew it was something simple. I actually remembered the other approach too, where you replace f'' with r^2, f' with r, and f with 1, and then solve for what r is. But either approach gives the same result. Thanks again though.