All Questions
Tagged with theoretical-chemistry energy
11
questions
3
votes
0
answers
85
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State-of-the-art results on molecular vibronic energy calculation
Could someone kindly point me to the latest records in scale, accuracy, or timescale for molecular vibronic energy calculation?
I tried to start with Google Scholar: https://scholar.google.com/scholar?...
- 245
2
votes
0
answers
95
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What is the largest known zero-point energy for a molecule?
I was surprised to find out that the zero-point energy (ZPE) for the ground state of $\ce{BH3}$ is a few thousand $\pu{cm-1}$, because for molecules I usually work with, it's much smaller. Does anyone ...
- 1,452
6
votes
2
answers
325
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Tunneling in chemical reactions
We know that quantum tunneling is the reason behind several natural phenomenon like alpha decay and thermonuclear fusion inside the stars. How can it influence chemical reactions by tunnelling a ...
6
votes
1
answer
283
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What advantage is there in reporting the Lennard-Jones well depth in wavenumber units?
The Lennard-Jones well depth $\epsilon$ is typically given in energy units ($\mathrm{kJ}$ or $\mathrm{kcal}$; sometimes per mole). Jasper and Miller, however, reported $\epsilon$ values in reciprocal ...
- 4,265
1
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0
answers
52
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What's causing my energy calculations to be wrong?
I'm calculating the energy density of certain flammable compounds in MJ/kg. To do this I compare the sum of the bond strengths of the reactants to the products and then extrapolate the energy density ...
- 21
7
votes
2
answers
1k
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How to explain Born repulsion between ions in gas phase?
In simple terms, the collision of two atoms $\ce{A}$ and $\ce{B}$ will result in ions $\ce{A^+}$ and $\ce{B^-}$ if $$I_a(\ce{A})+E_a(\ce{A})<I_a(\ce{B})+E_a(\ce{B})$$ where $I_a$ and $E_a$ are the ...
- 7,101
8
votes
1
answer
172
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Ballistic behavior of molecules on potential energy surfaces
I came across the following sentence in a publication$^1$: "At this point we have to remember that the computed MEP path [sic] represents the reaction in the absence of any kinetic energy, while in ...
- 4,723
4
votes
1
answer
208
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Plasma creation and condensation
Every chemical has a decomposition temperature. My understanding is that above that temperature molecular bonds are broken. And if we raise the heat high enough then all molecular bonds will break ...
- 3,340
13
votes
3
answers
3k
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Is the transformation of pi bonds to sigma bonds always energetically favorable?
Is the move from pi bonds to sigma bonds always favorable?
My professor claims so, except in the case of conjugated pi bonds. I can see how pi bonds going to sigma bonds might be favorable; I know ...
- 19k
3
votes
1
answer
3k
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What does reaction exothermicity say about the stability of molecules
If a reaction is exothermic it means that the energy state of the products is lower than that of the reactants so this will be the state that 'nature' will naturally strive for. Often you see that ...
- 6,750
7
votes
1
answer
671
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Algebra of conserved quantities for chemical reactions
So there is the standard formation enthalpy $\Delta H^0_f$ and there is also formation entropy.
Are there more (independent) quantities? What about the heat capacity? Is there a general theoretical ...
- 1,012