All Questions
Tagged with quantum-chemistry molecular-orbital-theory
151
questions
8
votes
2
answers
612
views
Mulliken Labels: How do I tell apart E, doubly degenerate, symmetry apart from T, triply degenerate, symmetry for a molecular orbital?
With A and B, it's pretty simple. If you rotate the molecule about its principle axis to where the orbitals line up, and the signs change, it's Mulliken label has a B. otherwise, it's A.
I heard E ...
- 109
2
votes
0
answers
212
views
Why is cyclohexane more polarizable than benzene?
Looking at figure 4.2 here, we can see experimentaly that cyclohexane is more polarizable than benzene.
Why is this the case?
Intuitively, I would think that because the orbitals in benzene are more ...
- 31
-4
votes
1
answer
28
views
Why is there a point of orbits along with quantization in case of energy gaps?
As per my textbook and online sources. The definition of Energy bands I have found is this:
A) Energy levels:
( In a simplified view of an electronic structure of a single atom or isolated molecule.
...
- 412
2
votes
1
answer
203
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How do the orbitals in atoms synchronize their phases during the formation of a bond?
Suppose I have two hydrogen atoms, each with one electron in their 1s orbital. Then we can represent the wave functions of these two as say $|\Psi\rangle_1$ and $|\Psi\rangle_2$ for each of the two ...
- 307
6
votes
0
answers
78
views
Why SCF-MO methods fail when treating bond-breaking processes?
I'm currently studying the EVB(Empirical Valence Bond) approach. While reading on this article (https://pubs.acs.org/doi/10.1021/ja00224a011), the author mentioned about the usage of SCF-MO formalism ...
- 221
-4
votes
1
answer
219
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What is the molecular orbital diagram of hydroxide anion? [closed]
Context
I am a teacher, and, during a class, my student asked me to draw the molecular orbital (MO) diagram of the hydroxide anion ($\ce{HO-}$). First, I made the diagram on the left, and then, when ...
- 2,304
-1
votes
1
answer
150
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If atomic orbitals are orthogonal, how can one mix then in Molecular Orbital Theory?
If two molecular orbitals are orthogonal, their net overlap is 0. Which means that the mixture of them would result in no observable change in any of the orbitals if they occur. However, this ...
2
votes
1
answer
90
views
What can visual observations of pi-bonding MOs explain about LCAO expansion coefficients?
For examples of CO and N2, what can their MOs tell us about their expansion coefficients?
I've thought that in N2, its symmetric so the expansion coefficients would be equal from the pi-bonding MO due ...
- 137
1
vote
2
answers
311
views
Molecular orbital picture in conjugated molecules - double bonds
I am a not a chemistry student but a physics student. Nevertheless, I am quite familiar with molecular orbital theory and similar quantum chemistry concepts. However, I have problems understanding the ...
- 121
0
votes
0
answers
365
views
Energy of a molecule using MOs diagram (case of CH4)
I'm trying to find the ground state energy of CH4 in order to compare it with simulations I made. I came across this diagram of energy (not sure it gives the true energies though, if you could confirm....
- 39
2
votes
1
answer
267
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Is there a difference between Hartree-Fock method and LCAO?
I have to dive in some quantum chemistry for a quantum machine learning project and I came across the so-called Hartree-Fock method.
In one of the reference I used, they considered electrons as ...
- 39
0
votes
1
answer
280
views
Would a hypothetical Og2 +235 form a chemical bond?
In a hypothetical (?) Og2+235 we would have a simple sigma bonding orbital occupied by one electron (leading to a bond order of 1/2). But how to take into account the giant repulsion of the two nuclei?...
user128572
1
vote
0
answers
58
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Reproducing Hydrogen Molecule Hamiltonian in OpenFermion
I am learning quantum chemistry at the moment and I'm trying to understand the Hamiltonian generated by the OpenFermion package. I'm now stuck at understanding how openfermion calculates the ...
- 11
4
votes
1
answer
265
views
Self Consistent Field method and LCAO
I am reading about the Self Consistent Field Method and Linear Combination of Atomic Orbitals.
Suppose we have one electron and one nucleus, then we can solve the Schrodinger equation explicitly.
If ...
- 43
1
vote
1
answer
90
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On the energies of molecular orbitals
I found a useful (though simplified) scheme illustrating the energies of atomic orbitals, in crescent order:
I wonder if there was an analogous (simplified) scheme or rule for molecular orbitals, at ...
- 119