All Questions
Tagged with quantum-chemistry density-functional-theory
85
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How to find the global minima of a supramolecular complex in computational chemistry?
So this is more of a complex problem, and my masters thesis could greatly benefit if I find an answer to this.
Essentially, I have a supramolecular inclusion complex. There is this molecule A (the ...
- 11
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157
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N2 HOMO-LUMO Gap calculation
I am thinking about calculating the HOMO-LUMO energy gap for $\ce{N2}$ molecule.
I thought I could model this as a particle in a box problem to find $E_\text{HOMO}$ and $E_\text{LUMO}$.
The formula I ...
- 151
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Can geometry of a molecule change when the spin-orbit coupling is taken into account? [closed]
Cross-posted on MMSE.
Is there any evidence that spin-orbit coupling (SOC) leads to significant changes in atomic structure? Using DFT, I am getting different relaxed lattice constants when I take SOC ...
- 629
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54
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Effective Core Potentials and their "corresponding Pople" basis set
Reading through a handout from Yale shows the author correlating the ECP with Pople basis sets. The author of this says the corresponding basis set for SDD is 6-31G, Def2TZV as 6-311G, LANL2MB as STO-...
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35
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How can I calculate the electrostatic energy between two fragments?
I have a 2-fragment molecular complex with partial charge transfer from fragment 1 to fragment 2. The binding energy is ~0.3 eV and I want to evaluate what fraction comes from electrostatic attraction....
6
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Are there examples of publications using DFT instead of HF as a coupled-cluster reference?
I have been searching for a while, and only managed to find an article by M. Saitow,[1] where CAM-B3LYP orbitals are used. I was wondering if this has been done elsewhere.
It was recommended to me by ...
- 61
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28
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How to obtain reliable ligand binding energy in QM manner?
I wish to compute the binding energy of the ligand to the known cavity of the receptor.
My idea was to:
Perform docking to the recognized binding site using AutoDock Vina
Export bound ligands and ...
- 139
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25
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Rationalisation of stabilising dispersion interactions in HgS via QM
It is well-known that mercury(II) sulfide, HgS, is extremely inert- for example, it has one of the lowest solubilities of nearly all known compounds in water(check Wikipedia). There are two well-known ...
- 725
3
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169
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Modelling barrier-less reactions
I am currently exploring a few dissociative reactions whose PES is barrierless (no first order saddle point). I have found a few approaches in literature like flexible nudged elastic band theory, ...
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470
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Why do DFT calculations output molecular orbitals?
My understanding is that DFT finds the electron density which minimizes some energy functional. How does it make the connection from this optimized density to molecular orbitals?
- 211
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What is the physical significance of the damping function in calculation of vdW interaction energy?
In order to take care for the singularity (also removing the double counting of exchange-correlation) obtained with this expression,
$$E_\mathrm{vdW} = \frac{C^6}{R^6}$$
many type of damping functions ...
- 181
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284
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Physical origin of induction and dispersion energies
I am reading this book on non-covalent interactions. Chapter 1 states that there are 3 types of non-covalent interactions:
Electrostatic interactions, which are just the coulomb interactions between ...
6
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1
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148
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How can I formally justify the description of an electronic excitation that includes only the relevant orbitals?
I am writing a small program to animate electronic transitions.
To do this, I am animating a Rabi cycle for a single electron as it moves from an occupied into a virtual orbital.
The on-resonance ...
- 63
1
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55
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In Kohn Sham DFT, what do we know theoretically about the exchange correlation energy?
As I understand Kohn Sham theory, it is proposed that the ground state energy for a molecule can be derived from the ground state of a fictitious set of non-interacting electrons moving in a ...
- 11
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58
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Comparing geometries and substrates calculated with DFT for different pathways
As DFT calculation is an excellent tool for confirming and understanding experimental results, I got deep into this field as organic chemist. I successfully isolated interesting transition states (TS) ...
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