Schroedinger equation with angular momentum operators

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Discussion Overview

The discussion revolves around the formulation of Schrödinger-like equations for the orbital angular momentum operators \(L^2\) and \(L_z\) in quantum mechanics. Participants explore the nature of these equations, their validity, and the context in which they apply, particularly focusing on eigenvalue equations and wavefunctions.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant proposes the equations \(L^2|ψ=l(l+1)ħ|ψ\) and \(L_z|ψ=mlħ|ψ\) as representations of angular momentum operators.
  • Another participant points out a potential issue with the units in the first equation, suggesting that the left and right sides do not match.
  • A third participant clarifies that the equations are eigenvalue equations that hold true only for wavefunctions that are eigenfunctions of the respective operators, and not for general wavefunctions.
  • This participant also questions the characterization of the equations as "Schrödinger-like," noting they do not describe time evolution of the wavefunction.
  • The original poster expresses confusion about the question's intent, indicating they are seeking a general waveform and revising their equation to \(E|ψ(t)=L^2/2I||ψ(t)\), while still being uncertain about how to incorporate \(L_z\) as an operator.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of the proposed equations or their characterization as Schrödinger-like. There is acknowledgment of the specific conditions under which the equations apply, but no agreement on a definitive formulation.

Contextual Notes

There are limitations regarding the assumptions about wavefunctions and the specific context of the equations, as well as unresolved questions about the intended meaning of the original question.

damien88
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Hi, I have just started looking at angular momentum in quantum mechanics and I am considering the question, ''Write down the Schrödinger-like equations for the orbital angular momentum operators L^2 and Lz. Would I be correct in thinking this would be;

L^2|ψ=l(l+1)ħ|ψ
Lz|ψ=mlħ|ψ


Thanks in advance
 
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If I understand your question, you are close. Take a look at the units of the first equation, the left and right sides don't match.
 
Those are Eigenvalue equations, and are true if your wavefunction are eigenfunctions of the respective operators with those eigenvalues. They are not true for general wavefunctions.

I also wouldn't call them Schroedinger-like, since they do not tell you the time evolution of the wave-function. I don't really know what you are looking for though.
 
The question itself has been lifted straight from a text and that's what is causing me some issues as I don't fully undertsand exactly what it is looking for.I believe it is just the general waveform I am looking for in this instance.

edit:

Ok, so now I have

E|ψ(t)=L^2/2I||ψ(t)

but I ma still unsure as to how this equation would look using Lz as the operator.
 
Last edited:

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