All Questions
Tagged with symmetry physical-chemistry
26
questions
3
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0
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27
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What prevents an octahedral complex from always assuming the quadratic planar limiting case, due to the Jahn–Teller distortion?
When a given high-spin complex is Jahn–Teller distorted, this does not change the relative position of the total energy of the complex (assuming $\mathrm{d^{10}}$ configuration).
Indeed, the ...
- 83
2
votes
2
answers
520
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What does the 2 in t2g stand for?
I have read so far that it is about whether the d-Orbital is symmetric to a C2 element perpendicular to its main rotational axis. If all the given orbitals in a group are symmetric to that element, ...
- 83
7
votes
2
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850
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Why is prismane explosive but cubane is not?
So I was reading about polyhedral hydrocarbons, because I dig the topic, and I read (admittedly on wikipedia entries... But they cited papers, I swear!) that prismane is explosive due to the massive ...
- 731
2
votes
3
answers
432
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Planes of symmetry of a molecule
Are we limited to use only xy, yz and zx planes to check for planes of symmetry of a molecule? Because I see a plane of symmetry in the following molecule through the two shown H atoms or OH groups. ...
- 31
3
votes
1
answer
178
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Solution of the Roothaan Equations of H2 by Symmetry Arguments
FWIW my background is in physics and maths, but I am just starting a chemistry PhD (the last time I took a chemistry class was high school). I have only some background in representation theory, and ...
- 141
2
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0
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59
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Is there a better coordinate framework and symmetry operator for constructing molecular orbitals of molecules with higher-order geometry?
The following excerpt is taken from [1] (with a few rewording, emphasizes are mine).
In an attempt to construct molecular orbital (MO) of any molecule, one needs to determine the symmetries of ...
- 639
4
votes
0
answers
89
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Symmetry Operation on Product of Functions
In regards to direct product representations, I'm trying to find a proof for:
$R(X_iY_j)=R(X_i)R(Y_j)$
Where $R$ is a symmetry operation of a group and $X_i$ and $Y_j$ are members of different basis ...
- 41
2
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1k
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What is the precise meaning of "in-phase" (and "out-of-phase") in this context?
I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled Symmetry: Infrared and Raman Active Vibrations, the author says the following:
...
- 1,083
0
votes
0
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107
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Symmetries and degeneracies of the s,p, and d orbitals
Consider the molecular AB_8 (complex with central atom A and 8 B ligands (coordination number 8), for which I determined the point group D_4d) and determine the symmetries and degeneracies of the s, p,...
- 341
10
votes
2
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3k
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Is there a physical explanation why benzene's pi molecular orbitals in a Frost circle are degenerate but pyridine's are not?
From here, the Frost Circles for both benzene and pyridine:
The $\pi$-MOs formed by 6 $\pi$-AOs of an aromatic ring are:
Listed with respect to the ordering in the above image, these MOs in benzene'...
- 1,648
5
votes
1
answer
2k
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For two compounds that are symmetrical, why does the more compact one have a higher melting point?
In this post, I refer to two molecules B (Di-tert-butyl ether) and C (Dibutyl ether).
Wikipedia: Di-tert-butyl ether (B)
b.p. 107.2 C
m.p. - 61 C
...
- 155
6
votes
1
answer
1k
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Rotovibrational selection rules for symmetric tops
The selection rules for symmetric top molecules are
$\Delta J = 0, \pm1$ and $\Delta K = 0$ for $K \neq 0$ (parallel transition)
$\Delta J = \pm1$ and $\Delta K = 0$ for $K = 0$ (parallel ...
- 1,696
10
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171
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In a molecular dynamics context, is the methyl rotation in propene a symmetric or asymmetric internal rotor?
In a prior question, I asked about the (a)symmetry of the potential energy surface of the methyl rotation of propene. In that context, the kinetic energy of the nuclear motions is of course assumed ...
- 17.4k
9
votes
1
answer
505
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Does the methyl rotation in propene have a symmetric or asymmetric potential energy surface?
Depending on how one imagines the methyl rotation of propene to occur, it seems like it could exhibit either a symmetric or an asymmetric potential energy surface. If the $\ce{H2C=CH\! -}$ portion ...
- 17.4k
25
votes
1
answer
4k
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What is the mathematical basis behind the Jahn-Teller effect?
Both first-order and second-order Jahn-Teller distortions play a very important role in chemistry.
It is often said that the Jahn-Teller effect is based on symmetry arguments, and hence nothing can ...
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