Talk:Linear combination of atomic orbitals

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Overlap Integral[edit]

Wikipedia doesn't seem to have a reference to "overlap interval" which is required by the "Linear combination of atomic orbitals molecular orbital method". "Overlap integral" accounts for overlap in atomic orbital wavefunctions. My reference, "Tinkham M, Group Theory and Quantum Mechanics, Dover, 2003, page 214" illustrates the use of the overlap integral in a specific example. A more general description is needed. 150.203.2.85 01:18, 30 November 2005 (UTC)[reply]

I have now found a definition from the Glossary of Terms Used in Theoretical Organic Chemistry provided by the International Union Of Pure and Applied Chemistry (http://www.iupac.org/reports/1999/7110minkin/o.html):

Overlap integral - The integral defining the summation over the space of the overlap of the electron density of two orbitals. 150.203.2.85 01:32, 30 November 2005 (UTC)[reply]

History[edit]

The article has this about the history of LCAO, "It was introduced in 1929 by Sir John Lennard-Jones and extended by Ugo Fano. It was indeed first put forward by Lennard-Jones, but what was the extension by Fano. Can we have a reference for it. I would also say that it was extended in the early days by Mulliken, Hund, Hückel and Coulson. --Bduke 07:56, 10 June 2007 (UTC)[reply]

I corrected this. See discussion on my talk page with several editors. --Bduke 00:58, 16 June 2007 (UTC)[reply]

Symbols[edit]

I attempted to make the symbols agree with p. 31 of IUPAC green book. --Bduke 00:58, 16 June 2007 (UTC)[reply]

Point that could use clarification[edit]

I'm under the impression that there's some relationship between this article and the article Tight binding. But neither article explains that relationship. Could someone add that information if they know it? Or, if appropriate, merge the two articles? --Steve (talk) 03:39, 17 August 2008 (UTC)[reply]

Good point. I'll think about it. Tight binding is a physics term while LCAO is a chemistry term. It will need care.

LCAO: What's the point? Some intuition please[edit]

I came across this topic while grading papers and I have long since forgotten what LCAO physically represents. On what basis does it work? I get the math, but I'd like the physical intuition. If someone could provide that in the article, that'd be great. 68.126.187.64 (talk) 20:08, 7 November 2010 (UTC)[reply]

As odd as this may sound, the sentence describing the math formula is actually a pretty good explanation of the the whole idea. Basically you have a bunch of pieces contributed by the atoms, and the molecular result is just various recombinations of various amounts of those pieces. Physically a molecule is just a combination of atoms, so molecular features are composed of combinations of atomic features? Is that the level of explanation or analogy that is needed? Maybe the lede starts off too technically, and should describe that sort of basic idea before delving into the quantum details of what and how it actually happens? DMacks (talk) 20:16, 7 November 2010 (UTC)[reply]

That sounds like a good start. I'm not sure why superposition works. My background is not in chemistry. It's in engineering. I took one course on this sort of stuff and the only thing I can think of is that there is some sort of linear operator involved (like a derivative or integral). The history is fun (e.g. person X reported this first in year Y), but I would like to see more of how the person proved it. Preferably in layman's terms first. Thanks for your response. 68.126.187.64 (talk) 20:40, 7 November 2010 (UTC)[reply]

Quick point[edit]

The last reference is wrong, but I don't know how to correct it. The issue number in Science is 3784, not 3785: every other part of the reference is correct. Could anybody change this... thanks. Nessa Carson (talk) 18:41, 29 December 2010 (UTC)[reply]

π bond formation[edit]

How LCAO only forms sigma bond not pi bond? apurva_thatsit 07:58, 23 July 2021 (UTC)

It does not. Have a look at the LCAO approach for benzene. You will find 3 MOs for the 6 electrons in the pi system. --Bduke (talk) 08:19, 23 July 2021 (UTC)[reply]