Separation of variables for non-central potentials

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Discussion Overview

The discussion revolves around the separation of variables for non-central potentials in various coordinate systems, particularly focusing on the potential V(r,θ) and its separability in spherical and potentially other coordinates. Participants explore theoretical aspects and references related to this topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the separability of the potential V(r,θ) in coordinates other than spherical coordinates, suggesting the form V(r,θ)=u(r)+f(θ)/r².
  • Another participant proposes the use of parabolic coordinates as a potential alternative for separation.
  • References to Landau and Lifgarbagez's work on quantum mechanics are made, indicating a discussion of separability in various coordinates.
  • A participant mentions Morse and Feshbach's book, noting it discusses separation of variables in linear PDEs, though the specific volume is not recalled.
  • A more specific potential is presented by a participant, which includes terms involving constants b, c, d, and f, and asks about its separability in other coordinates.
  • Concerns are raised about the generality of the functions u(r) and f(θ), suggesting that if they are completely general, finding another factorization may not be feasible.
  • One participant seeks examples of other non-central potentials that could be separable in different coordinates, expressing a desire for input from experts in the field.

Areas of Agreement / Disagreement

Participants express differing views on the potential for separability in various coordinate systems, with no consensus reached on specific alternatives or the generality of the functions involved.

Contextual Notes

There are limitations regarding the assumptions about the forms of the potentials discussed, and the specific conditions under which separability might hold are not fully resolved.

dongsh2
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Dear Everyone,

I have a question about the separation of variables for non-central potentials (r, \theta, \phi). In spherical coordinates, such a potential V(r,\theta)=u(r)+f(\theta)/r^2 can be separated. Who knows it could also be separated in other coordinates? Many thanks.
 
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Maybe parabolic co-ordinates. Landau Lifgarbagez, Quantum mechanics, discusses the separability in quite a range of different co-ordinates.
 
There's also the famous book by Morse and Feshbach (I don't remember exactly which volume) which discussing the separation of variables in a linear PDE.
 
DrDu said:
Maybe parabolic co-ordinates. Landau Lifgarbagez, Quantum mechanics, discusses the separability in quite a range of different co-ordinates.


Thanks. But using parabolic ones, how to separate the potential V(r,\theta) to the sum of those variables in parabolic ones.
 
dextercioby said:
There's also the famous book by Morse and Feshbach (I don't remember exactly which volume) which discussing the separation of variables in a linear PDE.

The question is following. For a non-central potential

V(r,\theta)=r^2/2+b/r^2+(c/r^2) [ d/sin^2(\theta) cos^2(\theta) + f/sin^2(\theta)], where b,c,d,f are constants.

We have separated it in spherical coordinates and published. I try to find the possibility in other coordinates.
 
Maybe you could be more specific about the potential you have in mind. If u(r) and f(theta) are completely general then I don't think that you can find another factorization.
On the other hand there are other non-central potentials which aren't of the form you specified and which are separable.
 
This potential was separated and studied last year in spherical coordinates. Which potential (non ours) could be separable in other coordinates? Could you pls tell me? Thanks.

I have sent this question to my friends in USA and France, but I have not received their reply. They are expert in this field.
 

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