Quantum numbers in wikipedia's table

Click For Summary

Discussion Overview

The discussion revolves around the interpretation of quantum numbers as presented in a Wikipedia table, specifically addressing the values related to total angular momentum and the conditions under which certain values are dashed. Participants explore the implications of these values in the context of quantum mechanics, particularly focusing on the rules governing the projection of total angular momentum.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why certain values in the quantum numbers table are dashed, specifically for j=l-s, given l=1 and s=1/2.
  • Another participant points out a potential violation of the rule regarding the projection of total angular momentum, noting that mj must satisfy specific conditions.
  • There is confusion expressed about the range of mj values, particularly regarding the requirement that |mℓ + ms| must be strictly less than j.
  • A later reply clarifies that if j=1/2, mj cannot equal 3/2, as mj values are limited to -1/2 or 1/2.
  • Participants discuss whether the condition should state |mℓ + ms| ≤ j instead of < j, suggesting a possible typographical error in the original source.

Areas of Agreement / Disagreement

Participants express confusion and debate over the interpretation of the quantum numbers and the associated rules, indicating that multiple competing views remain regarding the correct formulation of the conditions for mj.

Contextual Notes

Limitations include potential misunderstandings of the rules governing angular momentum projections and the specific conditions under which certain quantum numbers are valid or invalid, as well as the implications of the dashed values in the table.

fluidistic
Gold Member
Messages
3,932
Reaction score
283
Physics news on Phys.org
It violates the rule from

The projection of the total angular momentum along a specified axis (mj = −j, −j + 1, …, j), which is analogous to m, and satisfies mj = mℓ + ms where |mℓ + ms| < j.

(also on the webpage you referenced).
 
dextercioby said:
It violates the rule from

The projection of the total angular momentum along a specified axis (mj = −j, −j + 1, …, j), which is analogous to m, and satisfies mj = mℓ + ms where |mℓ + ms| < j.

(also on the webpage you referenced).

Ok thank you. But I am confused. They say that mj goes from -j to j via integers. And then that the modulus of mj must be strictly smaller than j. Thus how can mj be worth j?
 
Ah nevermind, I understood. In that example, if j=1/2, you can't get an mj=3/2 because if j=1/2 then mj=-1/2 or 1/2.
But shouldn't they say |m_l+m_s| =|m_j| \leq j rather than < j?
 
Yes, now that I think about it, it should include equality, too. Typo, maybe.
 
Ok thank you very much!
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 0 ·
Replies
0
Views
1K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
732