Degeneracy in Wave Function Energy States

  • Thread starter Thread starter delee2
  • Start date Start date
  • Tags Tags
    Degeneracy
delee2
Messages
2
Reaction score
0

Homework Statement


What is meant by the term degenerate when referring to wave function energy states? Do the wavefunctions for degenerate states necessarily look the same? Explain.


Homework Equations





The Attempt at a Solution


Degeneracy, in terms of wave function energy states, describes quantum states that occupy the same energy level . All orbitals of one shell have the same energy, meaning that they require the same energy to achieve this energy level. An example of this is in the hydrogen atom where the orbitals of its shell all have the same energy. This is likewise true for all one-electron ions such as He+ and C5+. Quantum numbers add up to the same energy
 
Physics news on Phys.org
You appear to have answered the question very well.

The wave functions do not necessarily look the same, that would essentially make them the same wavefunction. However take as example the energy associated with wavefunctions of the hydrogen atom. It is a function of the quantum number n, but these wavefunctions also have two other quantum numbers, l and m. So for the set of wave functions that have the same n, but different l, they are degenerate. They have the same energy, but a different l.

The different shapes given by there probability density:
HAtomOrbitals.png

Horizontally the quantum number l changes, and vertically the quantum number n changes. So for the bottom row, all 3 have the same energy (when ignoring fine structure and some other thing I have forgotten) and hence are degenerate.
 
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