Show that the total eigenfunction must be antisymmetric

In summary, the question asks for a demonstration that the total eigenfunction for two noninteracting particles at different distances must be antisymmetric in order to satisfy the Pauli exclusion principle. This means that the eigenfunction must be antisymmetric under particle exchange, resulting in a negative of the original eigenfunction.
  • #1
tarkin
13
0

Homework Statement


[/B]
By considering the eigenfunctions for 2 noninteracting particles at distances r1 and r2,
show that their total eigenfunction must be antisymmetric.
.

Homework Equations



Spatial wavefunctions:

Ψ(x1,x2) = 1/√2 [ ψA(x1B(x2) ± ψA(x2B(x1)]

Where + gives a symmetric wavefunction and - gives an antisymmetric one.




The Attempt at a Solution


[/B]
Hi, not really sure what to do with this one. I know that the Pauli exclusion principle says that the total eigenfunction must be antisymmetric for fermions. But the question doesn't mention fermions, just "2 noninteracting particles". I also know that the antisymmetric spin wavefunctions are associated with the symmetric spatial wavefunctions, and vice versa, to produce a total antisymmetric wavefunction, but I don't get why, which is what the question seems to be asking...

 
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  • #2
The question is very poorly worded. The wave function is anti-symmetric with respect to what? Bad questions have no good answers :frown:
 
  • #3
DrClaude said:
The question is very poorly worded. The wave function is anti-symmetric with respect to what? Bad questions have no good answers :frown:

Hi, sorry, I should probably have said a bit more in my OP. Presumably, in the question, the 2 particles are indistinguishable. So it means that eigenfunction must be antisymmetric under particle exchange. ie. that if the particles are swapped, this will give the negative of the original eigenfunction
 

1. What does it mean for an eigenfunction to be antisymmetric?

An eigenfunction is considered antisymmetric if it satisfies the condition f(-x) = -f(x). This means that when the input value is reversed, the output value is equal in magnitude but opposite in sign.

2. Why is it important for the total eigenfunction to be antisymmetric?

In many physical systems, such as atoms and molecules, the total wavefunction must be antisymmetric in order to accurately describe the behavior of particles with half-integer spin. This is known as the Pauli exclusion principle.

3. How is the total eigenfunction calculated?

The total eigenfunction is calculated by taking the product of all individual eigenfunctions and applying the appropriate symmetrization or antisymmetrization operator. This ensures that the resulting wavefunction is either symmetric or antisymmetric, depending on the nature of the system.

4. Can the total eigenfunction be a mixture of symmetric and antisymmetric functions?

No, the total eigenfunction must be either completely symmetric or completely antisymmetric. A mixture of both types of functions would not satisfy the overall symmetry requirements of the system.

5. What happens if the total eigenfunction is not antisymmetric?

If the total eigenfunction is not antisymmetric, then it does not accurately represent the behavior of particles in a system with half-integer spin. This can lead to incorrect predictions and results in physical systems.

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