All Questions
Tagged with symmetry quantum-chemistry
25
questions
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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101
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Point group of harmonic oscillator
The book Molecular Quantum Mechanics by Atkins and Friedman [1] says the point group of a harmonic oscillator is $C_\mathrm{s},$ composed by the identity operator $E$ and a reflection $\sigma_\mathrm{...
- 461
1
vote
1
answer
81
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What does it mean that a state belongin to a given irrep transforms like $Rx$, $Ry$ or $Rz$
The present question is related to this other question I did few days ago.
Given a point group and the list of the irreps (see for example here) the meaning of an irrep which transforms like $x$ or $x^...
- 267
7
votes
1
answer
411
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How do I show that a transition is electric dipole allowed with group theory/symmetry?
This is actually a follow up of this question
The follow-up is not because of the electric instead of magnetic dipole (this is trivial).
It is because I'm interested in extra info.
Suppose I have a ...
- 267
10
votes
0
answers
141
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Using symmetry and group theory arguments to explain iron(II) in a tetrahedral crystal field
I am trying to figure out how to explain $1s \rightarrow 3d$ spectroscopic transitions for $\ce{Fe^{2+}}$ in $T_\mathrm{d}$ symmetry. These transitions make up the pre-edge region in K edge X-ray ...
- 101
1
vote
0
answers
92
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High symmetry points and x-coordinates
Is it possible to work out the x-coordinates related to high symmetry points?
The software I'm using doesn't provide me with that, so I was wondering if there is a way to manually figure it out, as I ...
- 11
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
0
votes
0
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49
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are the exact and kohn-sham electron densities totally symmetric?
For any molecule with open or closed shells considering the electronic state to be the ground state:
Is the exact electron density totally symmetric?
is the Kohn-Sham electron density totally ...
2
votes
1
answer
91
views
How to find a symmetry group of a system if all the symmetry transformations do not obey closure and don't form a group?
For instance, consider a system with $p_x$ and $p_z$ orbitals at the vertices of a square (on xy-plane). A square by itself would have $D_4$ symmetry. However, because of the $p_x$ orbital; the $90^\...
- 21
1
vote
0
answers
42
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What is the link between the classical and quantum definition of the symmetry number?
From what I understand, the symmetry number for a molecule can be defined in 2 ways:
1. The quantum mechanical symmetry number corrects for overcounting the number of possible rotational states of a ...
- 647
2
votes
0
answers
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
2
votes
0
answers
51
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Determining symmetry correction by looking at rotational quantum states
I'm trying to understand the relationship between symmetry correction and rotational quantum states, particularly in the case of dipoles with identical atoms.
For an angular momentum quantum number $...
- 647
2
votes
0
answers
249
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Why is the transition (0,0,0) -> (1,0,1) observed in a gas phase IR spectrum of CO2?
Let ($v_1$,$v_2$,$v_3$) denote the vibrational state of $CO_2$.
Why is the transition $(0,0,0)\rightarrow (1,0,1)$ observed when the trasition $(0,0,0)\rightarrow(1,0,0)$ (asymmetric stretch) is not ...
- 21
0
votes
1
answer
116
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On the meaning of distinguishability, and wavefunctions for 3 electron atoms
In a 2-electron atom at lowest energy, the $(1s)^2$ is occupied and the electronic wave-function must satisfy anti-symmetry requirements in the particle coordinates, as the spatial wave function is ...
- 133
1
vote
0
answers
57
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Stabilizing donor-acceptor interaction between orthogonal orbitals in the SN2 transition state?
For the $\mathrm{S_N2}$ reaction between chloroacetone and iodide, my professor has drawn a donor-acceptor interaction between the iodine lone pair attacking the Cl-substituted carbon and the π ...
