This website has examples of molecules with more unusual symmetries, like T and Th. Pretty neat.
Incidentally, the thing about finding phasing of AOs in MOs with "symmetry reduction"? It's for finding patterns only, not for finding the actual phasing (which would indeed require the very annoying projection operator). For example, the pi system of benzene transforms as a2u + e1g + e2u + b2g. If we put this in Dinfinity-h, a2u is a sigma irreducible representation, e1g is pi, e2u is delta, and b2g is (kind of - 2 dimensional irreducible representations in Dinfinity-h is reducible in D6h) phi. Note the correspondence with atomic orbitals (s, p, d, f, ...) and count the number of angular nodes.
As the professor as so aptly puts it - "It's like solving differential equations: you make a guess then prove that your guess is right." Dammit.
It'd be nice if the university offers a "chemical application of group theory" course, but sadly, it doesn't.
The final is tomorrow - I am so freaking toast that it's not funny. Apparently it's equivalent to three midterms; this is not encouraging when I realize that there wasn't a midterm in which I finished even one minute early.
Friday, August 8, 2008
Molecules with Rarer Symmetries
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7 comments:
We DO have a chemical group theory class here, but I haven't taken it.
group theory is cool but it seems that anything that's interesting these days does not have symmetry anyway
felix, i think that only applies to biocrap :)
i can give you a zillion and a half organic semiconductors that are pretty symmetry-heavy :)
i guess you are right. but the question is how interesting are your zillion and a half organic semiconductors ...
and even if they are cool, i don't think people are able to model them, so i have to leave it to you guys anyway
go lit-stalk jean-luc bredas, among other people...ken houk, mark ratner (IIRC)...there is a TON of computational work to be done
at least my zillion and a half semiconductors have practical applications :P
i guess they are pretty cool. but the question is what you can really do as far a computation is concerned. it does not seem so promising, but of course i don't have the whole picture
Actually I thought the theory itself is pretty cool, but I guess the math is too well understood for people to actually do anything in it for its own sake any more...
(Knows nothing about semiconductors or stuff prefixed by bio-. Will stay out of it.)
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