Talk:Multipole moment

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Text and/or other creative content from Multipole moment was copied or moved into Multipole expansion with this edit. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists.

Article creation

Given the fact that multipole moments are used all throughout physics, engineering and even mathematics I am surprised this article does not already exist. I put up a late-night attempt at something halfway informative. I assume it will be edited many times! Perhaps I can work on this further... JustinWick 06:00, May 8, 2005 (UTC)

Multipole decomposition example

I believe it'd be really awesome to show some actual math for multipole decomposition. I think I can look up one in one of my old electromagnetism texts.

Yeah, that's great. I unfortunately know nothing about it, but I got here from the London Dispersion Force article - I assume it has a chemical/atomic meaning too, relating to dipoles? If someone could add that, that would be brilliant.

Error?

The Text says its the decomposition of a function. Shouldn't it be the decomposition of a field?

What do you mean by field? Karol 09:16, 7 December 2005 (UTC)[reply]

Multipole Names

It would be nice to include the method for constructing multipole names, such as hexadecapole. Zeroparallax 07:42, 15 March 2007 (UTC)[reply]

Formula missing descriptions

The section Multipole moments#Molecular electrostatic multipole moments introduces a lot of terms without any explanation. Some examples:

What is the multipole expansion expanding?
What are Racah's normalization and the Condon-Shortley phase?
What are $M_{0}^{0}$ , etc., and how are the expressions for them justified?
Ditto for $C_{1}^{0}$ , etc.

More explanation, links or citations are needed to make this article comprehensible. --RockMagnetist (talk) 14:14, 13 October 2010 (UTC)[reply]

Answers:

A potential (for instance due to electric charges), see the sentences in the lede: "multipole moments are the coefficients of a series expansion of a potential" and "a multipole expansion provides an exact description of the potential and generally converges under two conditions:"
See solid harmonic referred to in the same sentence: "regular solid harmonic function in Racah's normalization". I will give Condon-Shortley phase a wikilink.
$M_{0}^{0}=\langle \Psi |Q_{0}^{0}|\Psi \rangle$ , equation is in article with $\ell =m=0$ substituted. For justification see expectation value, which I will link to.
Real form of the complex $Q_{\ell }^{m}$ , see article.

--173.228.47.88 (talk) 17:09, 27 March 2012 (UTC)[reply]

Thank you. I removed the missing descriptions tag. RockMagnetist (talk) 18:50, 27 March 2012 (UTC)[reply]