Talk:Atomic units

Comparison with Planck units?

I propose to delete the section "Comparison with Planck units". As far as I can tell this section does not say anything interesting. The page natural units has a much more comprehensive comparison and would be better suited for these random, unreferenced comments. Johnjbarton (talk) 22:59, 2 January 2024 (UTC)

I wholeheartedly agree. —Quondum 23:36, 2 January 2024 (UTC)

No objection. It can always be restored (and redone in better shape) if sources turn up that make the comparison directly and in detail. XOR'easter (talk) 01:23, 3 January 2024 (UTC)

This is a good idea. Qflib, aka KeeYou Flib (talk) 22:08, 3 January 2024 (UTC)

 Done

"Systems used" section.

I think the "Systems used" is pretty effective in revealing an important issue in using atomic units. However it has some rough spots.

• "systems" is a bit puzzling to me. I think it is meant as "a consistent way of working" which I think is mostly called a "convention". And that is the word used in the second subsection. I would prefer "convention", because I don't know that formal rules are given explicitly, but in any case the same name should be used in both cases.
• We should avoid "many" and "common" unless we are basing these words in sources; it implies a poll of some sort. Simply having sources creates sufficient evidence without needing to count.
• I would like to replace or augment the names, eg 'Shull & Hall" with references.
• Ideally we would have some reference to a more systematic treatment of units/quantities/conversions given that the sources we reference are more explanatory.

Johnjbarton (talk) 16:44, 7 January 2024 (UTC)

All good points. In order:

• I have effectively eliminated the word "system", as I also lean to "convention" here.
• I agree about fuzzy words. I was trying to capture McWeeny's "[This] convention has much to recommend it and is tacitly accepted in atomic and molecular physics whenever atomic units are introduced", but we can work on improving this.
• Agreed about referencing. I intend to work on these crude placeholder references, but may be a little slow at this.
• I agree with your "ideally" objective, but I don't recollect seeing anything (in my meagre reading) that does the topic justice. I have seen a few sources that try but get it fundamentally wrong, showing just how tricky this topic is.

—Quondum 19:04, 7 January 2024 (UTC)

Requested move 8 January 2024

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: moved as requested per the discussion below. Dekimasuよ! 10:18, 15 January 2024 (UTC)

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Hartree atomic units → Atomic units – Rename to original title; discussed at Talk:Hartree atomic units § Article title (this is essentially a WP:COMMONNAME argument). —Quondum 19:18, 7 January 2024 (UTC) This is a contested technical request (permalink). SilverLocust 💬 08:13, 8 January 2024 (UTC)

• Comment: This would revert an undiscussed move from 2019, so I'm opening this RM to see if anyone wants to defend the current title. That move was in turn based on a sentence added to this article in 2007. SilverLocust 💬 08:13, 8 January 2024 (UTC)

Note: WikiProject Physics has been notified of this discussion. Vanderwaalforces (talk) 11:45, 8 January 2024 (UTC)

• Rename. As someone who does DFT calculations, I can say that the term "Hartree atomic units" is very rarely used. Standard is "atomic units", abbreviated to au.

Ldm1954 (talk) 14:04, 8 January 2024 (UTC)

• Rename The "Hartree" prefix is very rare. Johnjbarton (talk) 16:15, 8 January 2024 (UTC)
• Rename. "Atomic units" is definitely the common name. As I recall, the original move (not by me) was done in order to avoid any confusion between "Rydberg" atomic units/ "atomic Rydberg units" (which represents different conventions for energy and charge, I believe, and are used by some physicists; see this document for an example - http://ilan.schnell-web.net/physics/rydberg.pdf) and "Hartree" atomic units (which are used in ab initio and DFT calculations by physicists and chemists). This was well-intentioned, but the use of "Hartree" to modify "atomic units" is so rare as to actually create confusion in my opinion - and put Wikipedia in the position of creating new jargon. It would be better to rename this page as "atomic units" and, if necessary, have a second page named "Rydberg atomic units." Qflib, aka KeeYou Flib (talk) 18:11, 8 January 2024 (UTC)

  I see that I've repeated a lot of your points. I could just have said "as per Qflib". —Quondum 19:31, 8 January 2024 (UTC)

• Rename. (as nom) Reviewing searches, etc., it is apparent that "atomic units" appears extensively without qualification to mean the units originally proposed by Hartree. Where other "atomic units" are referenced, which is rare, the author generally disambiguates explictily. The dominance is a clear case of "atomic units" as the WP:COMMONNAME, and the current title seems to violate WP:CRITERIA: it is less recognizable, less natural, and less concise. From a WP perspective, it is incorrect to prefix a descriptor as a disambiguator to a standard name, which appears to have been the purpose of the previous rename In the literature, when "Hartree atomic units" occurs, (which is very rare), "Hartree atomic units" seems to be the shorter form of "atomic units of Hartree", a phrase that also occurs – which emphasizes that "Hartree" functions as a disambiguator and not as a part of the name. —Quondum 18:46, 8 January 2024 (UTC)
• Rename as proposed. I always thought this was a dumb title.--Srleffler (talk) 23:50, 13 January 2024 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Error in reference

In his base units table, McWeeny gives the dimension of action as A = MLT⁻¹, and this has been repeated in the table in the article. However, this should rather be A = WT = ML²T⁻¹. Or have I slipped up? —Quondum 14:25, 24 January 2024 (UTC)

That's certainly a typo. Evgeny (talk) 14:32, 24 January 2024 (UTC)

Thanks. I have fixed it; it seems to qualify for his error not needing to be pointed out in the article. —Quondum 15:09, 24 January 2024 (UTC)

Good catch. Embarrassed that I never noticed it. Qflib (talk) 17:23, 25 January 2024 (UTC)