Unanswered Questions
50 questions with no upvoted or accepted answers
2
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22
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Dataset of 2D/3D potential energy surfaces, excited states
I see several research papers with excited and ground state PES of different molecules showing level crossings and intersections. But, I do not find any database publicly available. Is there any ...
- 24.2k
2
votes
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82
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How to adapt Einstein summation subscripts from 3-Index to 4-Index tensors in Numpy's einsum?
I am trying to apply frozen core approximation in order to get the effect of the forzen core orbitals on the 1-electron and 2-electron Hamiltonian. According to the notes on Page 28, the electronic ...
0
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0
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28
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Quantum espresso pseudopotential convergence test
I generated a pseudopotential using atomic code(Quantum_espresso_6.7/atomic/src/ld1.x) and conducted convergence test. But as below, total energy tends to oscillation as ecut goes up.
(I performed a ...
- 44
3
votes
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answers
36
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How to correctly set the high-symmetry point path block when there are breakpoints in the recommended path?
I watched Dr. Mohan's tutorial video, and the settings he provided are as follows:
...
- 31
2
votes
0
answers
39
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Why is it PT symmetry not TP symmetry for Kramer Degeneracy
I understand that, under time reversal symmetry $H_k$ is transformed to $H_{-k}$, and only when we are at the points where k=-k such as in 1D the 0 and $\frac{\pi}{a}$ we would have degeneracy. And if ...
1
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52
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4
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27
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Understanding Oxidation States and Magnetic Moments in Multivalent Transition Metal Oxides
I’m reading some papers on using density functional theory (DFT) to study oxidation states in multivalent transition metal oxides, but I’m having difficulty interpreting the oxidation-state ...
2
votes
0
answers
41
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Is it reasonable to extract the Schottky barrier height from the zero-bias transmission spectrum?
The following question is based on discussions What's meaning of zero energy reference point in the energy-axis of zero-bias transmission spectrum extracted by sisl.get_sile('systemlabel.TBT....
- 167
1
vote
0
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29
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What is the relationship between electron-phonon coupling and nonadiabatic effects?
We know that under the Born-Oppenheimer (BO) approximation, the motion of nuclei and electrons is decoupled. However, when there is a degeneracy between potential energy surfaces, the nonadiabatic ...
- 11
2
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32
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How to start a unrestricted hartree fock (UHF) calculation with a custom guess in PySCF?
At first I want to do a UHF calculation of Li$_2$ dimer with spin=6 which shall give a sequence of $\sigma_{1s} \sigma^*_{1s} \sigma_{2s} \pi_{2p_x} \pi_{2p_y} \pi_{2p_z}$ (ordering might be wrong) ...
7
votes
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106
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What are some open problems to give interns?
Background: I'm a PhD student in Europe. Currently working on method/code development for computational chemistry. I have experience in DFT, code optimization, MD and Machine learning. But I'm not ...
- 1,115
1
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14
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which electrode is better when calculating seeback coefficient of a 2D semiconductor? bulk metal electrodes or semiconductor material itself
I would like to calculate the seeback coefficient of a 2D semiconductor.
I am thinking,
If I use bulk metallic electrodes, the semicondutor itself is not heated because transiesta can only put ...
- 4,394
0
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0
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7
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Siesta: Is that the advantage of using bulk-like metallic electrodes we can calculate channel materials of arbitrary length?
When we talk about adding extra screening layers to screen charges towards electrodes when we use semiconductors as electrodes,it sounds like the screening layers are not what we expect in our device. ...
- 167
0
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23
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siesta: Why are graphene nanoribbons with finite gaps used as electrodes without needing much more screening layers?
I did know one should use bulk-like metallic electrodes to avoid problems with screening and Fermi-level definition, and if I have to use semiconductors as electrodes, I need extra screening layers in ...
- 167
2
votes
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41
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siesta: Why is the current 0 for V < 0.8?
I met same problem in this questionsiesta: current-voltage threshold value is not consistent with the band gap value
After I finished this tutorial https://github.com/zerothi/ts-tbt-sisl-tutorial/tree/...
- 167