Talk:List of Hund's rules
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I noted this on the page for Term_Symbol as well, but perhaps this is a better place. On the page for Hund's_Rules, it states that they can only be used to determine the ground state, not to order the excited states by energy. However, on the Term_Symbol page it seems to use Hund's Rules for exactly this. I don't know enough about the subject to know where the error lies, but there certainly appears to be an inconsistency at present. --Westm 07:00, 21 September 2006 (UTC)
"For atoms with less than half-filled shells, the level with the lowest value of J \, lies lowest in energy. Otherwise, if the outermost shell is more than half-filled the term with highest value of J \, is the one with the lowest energy." This sentence is confusing me for the exactly half filled case. It says 'less than half filled shells...otherwise...more than half filled' what about half filled shells? This is made more confusing in the body, where it says 'The value of \zeta (L,S)\, changes from plus to minus for shells greater than half full.' Xaerocool 08:20, 27 October 2006 (UTC)
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[edit] what about when the subshells are full
A mention perhaps about the case of Zinc, where subshells are full (Example 2?) --sigs —Preceding unsigned comment added by 82.130.14.161 (talk) 22:23, 18 October 2007 (UTC)
[edit] There is an error in rule 2
Surely this should say that term energy is lowest when S is maximised. At the moment it says that term energy is highest when S is maximised, which I believe to be incorrect. <
I have now changed "highest" to "lowest". Dirac66 (talk) 03:38, 9 March 2008 (UTC)
[edit] Confusion about rule #1, and problems with rule #2
As far as I was aware there are only 3 Hund's Rules, and these appear as 2, 3 and 4 on the page. I have no idea what rule 1 is going on about, and the explanation given for it makes little sense to me - it mentions repulsion between protons, which has nothing to do with electronic configuration.
If I was to edit the page I'd remove all mention of this phantom 1st rule that is currently there, and re-number the remaining 3 rules accordingly.
Problem with the explanation given for rule 2 (which would be rule 1 if I editied the page as suggest above) are in the 2nd paragraph; It is often stated that this is the highest energy atomic state because it forces the paired electrons to reside in different spatial orbitals, and this results in a larger average distance between the two electrons, reducing electron-electron repulsion energy. But, in fact, careful calculations have shown that this explanation can be wrong, at least for light systems
To start with, the state with maximised paired electrons is the lowest energy state, not the highest. My understanding is that this arises from the Fermi Hole in the wavefunction of paired electrons reducing electron-electron repulsion. The article appears to disagree with me here; ...in fact, careful calculations have shown that this explanation can be wrong, at least for light systems. but no citation is given for this statement. Krusader86 (talk) 15:53, 28 November 2007 (UTC)
[edit] Spurious rule #1
Yes, Hund proposed 3 rules and not 4. See for example Miessler and Tarr "Inorganic Chemistry" (2nd edn 1999), pp. 358 and 360.
The current (9 Mar 2007) "first rule" in the article is spurious and was inserted by a very confused editor (or vandal?) on 4 November 2007.
Prior to that edit, the following statement was cited as the "first rule": Full shells and subshells do not contribute to total S, the total spin angular momentum and L, the total orbital angular momentum quantum numbers. This is in fact a true statement, but is usually presented as a preliminary statement and not as the "first rule".
I will renumber the rules, and reinsert the correct version of the preliminary statement. Dirac66 (talk) 04:21, 9 March 2008 (UTC)
