All Questions
Tagged with intermolecular-forces theoretical-chemistry
11 questions
16
votes
3
answers
4k
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Why does the exchange interaction in Hartree-Fock theory lower the total energy?
In Hartree-Fock theory, the expectation value of the total energy can be written as
$$E = \langle\Psi| H |\Psi\rangle = \sum_{a} \langle a| h |a \rangle + \frac{1}{2}\sum_{ab} \big( [aa |bb] - [ab|ba]...
- 746
14
votes
2
answers
2k
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How to identify hydrogen bonds and other non-covalent interactions from structure considerations?
Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically ...
- 44.4k
34
votes
2
answers
8k
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What is the exchange interaction?
As the wikipedia article for the exchange interaction so aptly notes, exchange "has no classical analogue."
How wonderful.
Exchange shows up essentially while enforcing the condition that two ...
- 13.2k
6
votes
1
answer
144
views
Is it possible to have a dispersion interaction with no inductive interactions?
In symmetry-adapted perturbation theory, the interaction energy of a non-covalently bound pair of molecules (it could be done to arbitrary order but is usually just pairs) is built up from a ...
- 13.2k
0
votes
1
answer
88
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Model of London forces and Hydrogen Bonding; the question is carried on forward, partially, as a personal question, from another question [closed]
Does Model of London forces and Hydrogen Bonding are themselves complicated and require multiple sub-models and assisted theories to explain its correctness.
I asked this question in the form (...
24
votes
3
answers
14k
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Is Hydrogen Bonding a Type of Dipole Dipole Interaction?
I understand that dipole dipole forces is due to the attraction of the different partials charges of atoms in different molecules due to their different electro-negativities.
For hydrogen bonding, ...
- 7,462
4
votes
1
answer
115
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Charge consistency in fragment qm/mm methods
I'm calculating the multipole moments on several fragments of a molecule. What are some procedures to ensure that the charges etc are representative of the complete molecule? How do I ensure I'm not ...
- 41
3
votes
1
answer
191
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How to get a protein's dihedral angles ordered by variance?
The setting: I want to simulate protein docking and let some dihedral angles vary, but in order to keep it low-dimensional I have to select those which are most likely to change.
What I've thought of ...
- 205
36
votes
1
answer
6k
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Natural Bond Orbital analysis: Significance of stabilization energy determined by 2nd order perturbation
PREFACE: I am no expert on this topic. My questions at the bottom may be off base. I have some experience with symmetry-adapted perturbation theory (SAPT) when it comes to analyzing intermolecular ...
- 4,637
2
votes
1
answer
278
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Questions about intramolecular interactions in AMBER forcefield
I am trying to run a molecular dynamics simulation with AMBER forcefield. However, it's the first time I use is, and while I know the form of the various intra- and intermolecular energy terms, some ...
- 23.9k
12
votes
1
answer
314
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Are buckminsterfullerene-corannulene complexes actually stabilised by π stacking?
According to wikipedia and the references given therein, $\pi\cdots\pi$ stacking interactions are the result of interaction between the quadrupole moments of two aromatic rings, rationalising the ...
- 10.9k