What is the ground state wave function of ortho-helium and its degeneracy?

In summary, the conversation discusses the construction of the ground state wave function of orthohelium, taking into account its triplet spin state and the requirement for an antisymmetric spatial wave function. The final result is a wave function with a minus sign and a triplet spin state, making it quadruply degenerate in terms of (l,m) values and 12-fold degenerate overall. However, the discussion also notes that this degeneracy only holds for single-electron atoms and may not apply to orthohelium.
  • #1
Oddbio
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I want to construct the ground state wave function of orthohelium.
Here is my reasoning, please let me know if I am correct or not.

[EDIT]
I forgot to add that for this post I am ignoring the electron-electron interactions.
[/EDIT]
Orthohelium has the triplet spin state which is symmetric. Because the total wavefunction must be antisymmetric that means that orthohelium must have an antisymmetric spatial wave function to go with the symmetric spin part.

However, I read that the ground state of helium in general MUST have a symmetric spatial wave function. Therefore that cannot also be the ground state of orthohelium.

So we must go to the first excited state, which can be written as:
[tex]u(r1,r2) = \frac{1}{\sqrt{2}}[\psi_{100}(r_{1}) \psi_{2lm}(r_{2}) \pm \psi_{100}(r_{2}) \psi_{2lm}(r_{1})] X[/tex]

where X is the spin wave function. Either singlet or triplet.

the 100 means (n=1 l=0 m=0) which must be true for the electron in the ground state:
the 2lm subscript is (n=2, l=0 or 1, m=-1 or 0 or 1)

Now, because orthohelium must have the X as the triplet spin which is symmetric, then we must use the minus sign in the equation to get the antisymmetric spatial state.

Therefore I get that the ground state wave function of orthohelium is:
[tex]u(r1,r2) = \frac{1}{\sqrt{2}}[\psi_{100}(r_{1}) \psi_{2lm}(r_{2}) - \psi_{100}(r_{2}) \psi_{2lm}(r_{1})] X_{triplet}[/tex]

Then also I am curious as to the degeneracy of the ground state of orthohelium.
IF I am correct, then would I be correct in saying that this ground state of orthohelium it quadruply degenerate?
Because we can have 4 different wave functions for the (l,m) values: (0,0) (1,-1) (1,0) (1,1)
and because the energy only depends on the n quantum number then all four have the same energy right?Any advice will be GREATLY appreciated.
Thanks.
 
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  • #2
This is correct up to the discussion of degeneracy. Assuming that the energy depends only on ##n##, the result would be 12-fold degenerate, as there are four equivalent spatial wave functions, and three spin states. In reality, the degeneracy of eigenstates of the same ##n## but different ##l## only holds for single-electron (hydrogen) atoms. So the ground state of ortho-helium has ##l=0##, ##m=0##, and is three-fold degenerate due to electron spin.
 

1. What is the ground state of ortho-helium?

The ground state of ortho-helium is the lowest energy state that the atom can exist in. It is the most stable configuration for this particular atom.

2. How is the ground state of ortho-helium determined?

The ground state of ortho-helium is determined by the arrangement of its electrons in the atom's energy levels. The electrons will occupy the lowest energy orbitals available, filling them up according to the Pauli exclusion principle and Hund's rule.

3. What is the difference between para-helium and ortho-helium?

Para-helium and ortho-helium are two different forms of helium that have different electron spin states. Para-helium has electrons with opposite spins, while ortho-helium has electrons with the same spin. This difference in electron spin states leads to different properties and reactivities between the two forms.

4. Why is the ground state of ortho-helium important?

The ground state of ortho-helium is important because it is the most stable state for this atom. This means that it is the state that the atom will naturally tend to exist in, and understanding its properties can help us better understand and predict the behavior of helium in various chemical and physical processes.

5. Can the ground state of ortho-helium be changed?

Yes, the ground state of ortho-helium can be changed through the application of energy. For example, if the atom absorbs energy, it can be excited to a higher energy state. However, once the energy is removed, the atom will return to its ground state. Additionally, chemical reactions can also alter the electron configuration and change the ground state of ortho-helium.

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