All Questions
Tagged with quantum-chemistry computational-chemistry
368
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Why Car Parrinello Molecular Dynamics doesn't need an SCF calculation at every time-step?
Reading the various terms of the Lagrangian in CP-MD I'm trying to understand why there is not an SCF procedure hidden there.
In fact, it seems to me like the second term of the Eulero-Lagrange ...
- 101
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67
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Finding the relative position of the molecule in the adsorbate and adsorbent by minimizing the Hamiltonian
I am trying to model an adsorbing process (or more precisely, Heterogeneous catalysis process between solid catalyst and gas reactants). One of the step is to minimize the Hamiltonian by optimizing ...
- 77
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36
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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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56
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Theoretic (QED) Atomic Ionization Energies Database?
The 2019 paper "QED tests with highly-charged ions" contains a survey of QED-calculated atomic ionization energies. I can manually copy the values of interest therein, but it seem that ...
- 251
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How to compute solvent reorganization energy in Marcus' non-equilibrium approach?
I try to solve the following equations for some system solvated in the water. The goal is to obtain value in kcal/mol. Unfortunately, I cannot reach the desired output. May someone help me?
The ...
- 103
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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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47
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Reduction of direct product representation
When we do the reduction of the reducible representation generated from the total wavefunction expressed as product of MOs of appropriate symmetry, we can find the direct sum of more than one ...
- 101
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54
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Group theory and exact Eigenfunctions of Hamiltonian
I think I've understand why the real Eigenfunctions of Hamiltonian belong to a given irreducible representation and I've read that also MOs have to transform as irreducible representation due to the ...
- 101
2
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42
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Commutating operators of angular momenta
I've studied the formal procedure to pass from the uncoupled basis set of individual angular momenta to the coupled basis set of total angular momenta for polyelectronic atoms.
I start from an ...
- 101
2
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80
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Derivation of the conversion of Gaussian type orbitals (in cartesian coordinates) to Gaussian type orbitals (in polar coordinates)
While studying basis sets, I came across Gaussian type orbitals (GTOs), which are used as atomic basis sets. I reviewed the polar form of these orbitals, which are very similar to hydrogen atom ...
- 21
6
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103
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Obtaining transition density matrix
I'm trying to assemble a transition density matrix on quantum computer using one-body excitation $\widehat{E}$ operator on 2 active spatial orbitals, i.e. on 4 spin-orbitals. The problem is, I need to ...
- 1,267
2
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1
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90
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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
-3
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161
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What does the χ (chi) symbol represent in a Slater determinant? [closed]
Context: Computational Chemistry
So, I am looking at the molecular orbital approximation, which allows the assumption that the overall wavefunction can be written as individual molecular orbitals
Ψ(r1,...
2
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80
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How to determine the unitary transformation from atomic orbitals to symmetry-adapted atomic orbitals of Ethylene
I am trying to find the unitary transformation matrix U from the atomic orbitals $|\mathbf{\chi}\rangle$ of ethylene to the symmetry-adapted atomic orbitals $|\mathbf{\chi}'\rangle$ of Ethylene, i.e $|...
