Quantum number and wave vector

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Discussion Overview

The discussion revolves around the relationship between quantum numbers (n, l, m) and wave vectors (\vec{k}) in the context of quantum mechanics and solid-state physics. Participants explore the implications of these concepts in different representations and their relevance in various experimental contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes that quantum numbers n, l, m can be seen as scaled wavenumbers that take integer values under certain boundary conditions, leading to a discrete set of allowed wavenumbers.
  • Another participant suggests that the quantum numbers and wave vectors represent different bases, with n, l, m being associated with a basis where Lz is diagonal, while wave vectors relate to momentum representations.
  • There is a mention of the relationship between quantum numbers and the position of the particle, particularly in the context of spherical harmonics.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between quantum numbers and wave vectors, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion highlights the dependence on specific experimental contexts and the implications of different representations in quantum mechanics, but does not resolve the underlying complexities or assumptions involved.

ewilibrium
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Hello!

Can you help me a question?

-The particle was describeb by 3 quantum number: n,l,m (not consider the spin).
-But in Solid books, writer often use wave vector [tex]\vec{k}[/tex] to describe state of particle. That is kx, ky and kz with 3 dimension of coordinate.

Then, what relation with 3 quantum number with 3 wave number?
 
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Your context is very vague, but based on what I've encountered in textbooks is that n,m,l are scaled wavenumbers, so that they can take integer values.
Normally the wavevector can take any value, but if you impose strict boundary conditions on the position (limit the position to a square well, or apply periodic boundary conditions) the allowed wavenumbers become a discrete set. For reference it is then sometimes useful to refer to the states by integers.
 
ewilibrium said:
Hello!

Can you help me a question?

-The particle was describeb by 3 quantum number: n,l,m (not consider the spin).
-But in Solid books, writer often use wave vector [tex]\vec{k}[/tex] to describe state of particle. That is kx, ky and kz with 3 dimension of coordinate.

Then, what relation with 3 quantum number with 3 wave number?

You are using different basis.

The first (nlm) is the Basis where Lz is diagonal, but you cannot diagonalized Lz simoultaneusly with Px (remeber that: P|k>=K|k>).
infact [Lz,Px]=Py and so on.

They are just 2 different Representations.
It depends which kind of experiment u have to perform.
 
Thanks you very much!
Then I can say n,l,m include posittion of the particle?
 
ewilibrium said:
Thanks you very much!
Then I can say n,l,m include posittion of the particle?

On the sphere obviously. see spherical armonics.

bye marco
 

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