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I strongly disagree with much of the format of the paper, and in particular with the definition given: "In chemistry, a molecular orbital (or MO) is a region in which an electron may be found in a molecule."
I know it's a definition often found in non-quantum chemistry books (organic chemistry, biology, general chemistry...) but to me it's essentially meaningless.
Then the definition continues:"Molecular orbitals are described by wave functions, mathematical solutions to the Schrödinger wave equation for a molecule, [...]" "They can be quantitatively approximated using the Hartree-Fock or Self-Consistent Field method."
Molecular orbitals are NOT solutions to the molecular Schrodinger equation; they arise in the context of independent-particle models/approximation of the exact Schrodinger equation, in particular the Hartree--Fock one. They are not "quantitatively approximated" approximated my the Hartree-Fock method, they are defined by it. —Preceding unsigned comment added by 128.40.5.101 ( talk) 19:12, 30 August 2008 (UTC)
The start of the page is (still? again?) really awful. I'll try to improve the beginning and Overview to start - the overview surely should be simple and not introduce lots of concepts only needed if you want heavy detail.... The first picture doesn't help much, being mainly of atomic orbitals. Dump it? Ian 09:18, 30 July 2007 (UTC)
9/7/2004 2105 MST
I'd argue that that this is a stub. It has quite a bit of information, plenty for the casual observer, but by the standard of someone who wants to do anything with it, not enough. If I wanted to put together a FMO diagram for LiH (classic problem) I'm not sure I could after reading this page.
A really nice page. However a couple of things aren't transparent,
Molecular symmetries]? map [stationary states]? to stationary states, so any collection of degenerate? molecular orbitals must transform according to some representation? of the [symmetry group]?. As a result, basis orbitals that transform according to different representations don't mix.
Could you make this a little clearer please, I can't make head nor tail of it.
Also
On the other hand consider a hypothetical molecule of H3, with the atoms labelled H, H', H". Then we would expect three low energy combinations:
1s + 1s" - 1s' Symmetric
1s - 1s" Antisymmetric
1s + 1s' + 1s" Symmetric
Is this correct ? The second combination has onlt 2 basis states and it's not blatenly obvious why the first is symmetric.
Theresa Knott
Is the LIGHT YEARS comment really correct? Got a tad confused there, can someone just see if that is a typo or something??
Ohm
The discussion on H3 is mostly incorrect. H3 is not C2v symmetry. It is a regular triangle - i.e. D3h. Many people of course discuss linear H3 as the transition structure for H exchange - H + H2 -> H2 + H, but the section here is neither of these things. I suggest someone who has more feel for the overall purpose of this article than I have has a go correcting it, but I might have a go later. Bduke 23:34, 1 November 2005 (UTC)
Actually, H3 does not have a minimum at D3h symmetry. Since there are three electrons, the lowest MO will be doubly-occupied, and at D3h, the remaining electron must be shared over a degenerate MO. This will Jahn-Teller distort away--probably to C2v. User:Ecbrown 20:47, 12 November 2006 (UTC)
This term handwaving sounds like American baloney to me. It is imprecise. When I was in school "hand waving" implied that mathematics failed, and the lecturer resorted to emphatic hand gestures to convince you he was right. It seems typical of American science that such a poorly understood colloquial term would end up in an encyclopedia. Whoever wrote that ought to get a job at NASA Frizb 16:11, 22 May 2006 (UTC)
The article might be a bit easier to read if the first sentence was split into two or three. Too many ideas in one sentence I think.
I think that the Dinitrogen example in section:MO diagrams is incorrect. Isn't the sigma bond order equal to the total number of electrons in sigma orbitals minus the total number of antibonding electrons in sigma orbitals all over 2?
Someone who knows more than me about this please make the correction. 130.102.128.60 01:48, 25 July 2007 (UTC)
While presenting at the 1979 Sanibel Symposium, I had the occasion to ask Per-Olov Löwdin for his definition of an orbital. Without hesitation, he told me that it was first used by Robert S. Mulliken "in 1925 as the English translation of Schroedinger's use of the German word, 'Eigenfunktion'." Mulliken had been working in Germany in 1925 with many of the founders of Quantum Mechanics and particularly in 1927 with Friedrich Hund on the beginnings of molecular orbital theory. Mulliken presented his work at that time in Physical Review. Löwdin told me to look there for the first use of a hydrogen "orbital" in English. He also agreed that a suitable definition of an orbital would be "a mathematical function that describes the wave-like behavior of an electron". I will edit the definition to reflect this usage of the term as a mathematical function, but also connect it to the more general description of an orbital as a "region of space" that can be calculated from the function. The advent of graphing calculators has enabled even high school students to grasp the definition of an orbital as a mathematical function. I invite educators to have their students graph the "simplified' 1s orbital, y = exp(-abs(Z.x)), where Z=1,2,3( Atomic Number). This simple exercise can display the effects of electronegativity and the fact that atoms and isoelectronic ions "decrease" their size in going to the right in a row in the periodic chart. The bonding and antibonding sigma MO can also be displayed by y = exp(-abs(Zx+1) + or - exp(-abs(Zx-1) . After graphing functions, students can grasp the idea of "combining" functions (atomic orbitals) to get other functions (molecular orbitals), and what is meant by the + and - signs or the red/blue, white/gray colors of the orbitals. As for some measure of proof, please see
Laburke ( talk) 22:26, 21 November 2008 (UTC)
There is not doubt that Mulliken first used the term "orbital", but the date is a problem. I doubt it is 1925 given that the publication of the Schrodinger equation was 1926. I have therefore removed it. This needs a source. What Per-Olov Löwdin told Laburke will not do, although I too remember Per-Olov, at a Sanibel meeting, crediting Mulliken with the use of the term, but I do not recall him mentioning a date. - Bduke (Discussion) 23:34, 15 February 2010 (UTC)
Please excuse the typographical error. I meant to write "in the 1920s..." not "in 1925" Laburke ( talk) 03:24, 28 April 2010 (UTC)
A group of chemistry undergraduates including myself have started major edits and additions as a class project in an effort to have the article upgrade to an 'A' rating or better. It will take several weeks or months for us to finish. -- 11:47, 4 February 2011 (UTC)
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In the section Molecular orbital there's a reference to a figure 6, while in the whole of the lemma only three pictures apear. As on this talk page there are some notifications of pictures to be removed from the commons, I suspect the problem is (partly) in this removal. I don't feel confident enough on the subject to correct the numbering, so please .....:-) T.vanschaik ( talk) 07:10, 21 November 2012 (UTC)
I have no reason to doubt the quality of this article. But it's troubling that some parts have no or few refs. Need to add refs, so sources are clear and to fulfill WP:VERIFY. It gives readers a way to go deeper in their study. It makes the content traceable, so questions that arise can be resolved starting at the ref. (Maybe the ref is not representative. Maybe it's a poor ref. Maybe it even has mistakes?) Until there are refs throughout, I can't send students here to learn. — Preceding unsigned comment added by 12.40.94.210 ( talk) 20:42, 11 December 2013 (UTC)
A good choice because acetylene is a little familiar. And good because it is a simple, linear molecule. But a student or other interested reader will have no clue what they are looking at. Maybe: Start with saying what the two-tone grey is peeking out (connect to H-C-C-H). Then explain the blue and red. Then make clear why two columns, and why multiple rows. If a ref can be given, good too. Thanks. — Preceding unsigned comment added by 12.40.94.210 ( talk) 21:26, 11 December 2013 (UTC)
The cycling movie/cartoon has a good, clear legend. (You could move the last sentence up.) The acetylene fig leg could use this kind of expansion.
You might consider adding a dihydrogen MO diagram. Having the MO diagr helps connect the good, active cartoon, to more widely seen figs. Even if deciding not to, the ordinate (energy) should be labeled, so it's clear that sigma is lower and sigma-star is higher in energy. Here are possible figs, one including g and u:
This would address confusion comparing double peak appearance in cartoon, and oval-of-revolution / spheres-touching-at-a-point ways of representing the MOs. And, Walsh mention anywhere? Thanks for work. — Preceding unsigned comment added by 12.40.94.210 ( talk) 21:49, 11 December 2013 (UTC)
In the header, "on an elementary level" redirects to "dumbing down". I assume this is a troll that has gone unnoticed so far. Can someone remove it?
-- 2A02:8070:E284:B100:6DC0:5429:40B4:DBC0 ( talk) 21:41, 14 November 2017 (UTC)