10
votes
Accepted
Difficulty in interpreting electronic band structures in solid state physics
One important step is to know how the Fermi energy ($E_F$) was treated. Some authors like to shift the band diagram after making $E_F=0$ (as looks like it was the case in the reference you cited) but ...
- 22.3k
9
votes
Accepted
What makes the inhomogeneous electron gas more interesting than its homogeneous counterpart?
The homogeneous electron gas is a fiction: it represents a system that is completely uniform and that has a constant, smooth positive background charge to make the system charge neutral.
However, the ...
- 18k
8
votes
Accepted
Simulated STM Image with Quantum-ESPRESSO's pp.x
A minimal input file
For simulated STM, you can use pp.x. A minimal input file might look like this:
...
- 2,101
8
votes
What makes the inhomogeneous electron gas more interesting than its homogeneous counterpart?
In contemporary Kohn-Sham DFT, the exchange and correlation energies are local quantities. If the electron density is slowly varying, the LDA form derived from a uniform electron gas is a zero'th ...
- 1,311
7
votes
I'm considering to take an introduction course with textbook "Materials Science and Engineering: An Introduction", as a beginner QE user. Is it okay?
I am no expert or experienced in this field. All my suggestions are based on my own experience as a beginner in matter modeling.
About the textbook
This textbook you mentioned is sufficient for a ...
- 2,101
7
votes
Accepted
Why do we not get DOS by summing over all the PDOS?
The fundamental problem is that the basis set used for the partial density-of-states (PDOS) does not span the plane-wave basis set space, so it is not usually possible to represent the Kohn-Sham ...
- 6,582
5
votes
Optimzation for Large supercell
It should be possible to use Quantum Espresso to handle more than 200 atoms.
I guess you are studying a surface, in that case, please note that in PW-based codes the vacuum makes your calculation more ...
- 967
5
votes
In solids physics, how are Van Der Waals forces modelled?
The documentation for pw.x, version 7.2, lists several different ways to compute van der Waals corrections:
Grimme's semiempirical DFT-D2 and DFT-D3;
Tkatchenko–...
- 766
4
votes
Accepted
Negative band gap in DFT calculations
Some materials erroneously give a metallic state even if it isn’t. Depending on what type of material and exchange-correlation functional you use, this can be more or less likely to happen. With ...
- 1,050
3
votes
Accepted
Can specifications of a second-order phase transition of a solid be obtained with the Hartree-Fock (or DFT) calculation?
In classic DFT approach you run geometry optimization for both phases which gives you electronic energies, then compute frequencies which gives you thermodynamic parameters, including tempurature-...
- 370
2
votes
How is magnetization of a solid obtained from electron density in a DFT framework?
The main keyword you are looking for is the spin-polarized DFT. Other keywords that might help you are the spin-density matrix, the Hubbard model (DFT+U), the Stoner Model, von Barth-Hedin spin-...
- 2,101
1
vote
The "Tetrahedron method does not include variations of the Fermi occupations" Problem
The issue has been resolved. It seems that it was caused by rounding the cell parameters to the sixth digit after decimal point instead of printing all 16 digits of it. (I was applying some strain and ...
- 401
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