14 votes
Accepted

Si energy band values are not matching with literature values

The y-axis corresponds to the direct eigenvalues from your DFT calculation. You need to set the valence band maximum to '0' manually. The DFT output of your calculation will give the highest occupied ...
  • 2,931
12 votes

How to generate the high symmetry paths for band structure calculations?

If you are really interested in learning how to generate the path, I strongly advice you to avoid using any automatic tool like suggested in previous answers. In the Wiki page entitle Brillouin zone ...
  • 19.3k
12 votes

How to generate the high symmetry paths for band structure calculations?

If the crystal unit cell is in a format readable by ASE, then you can use code that looks approximately like so: ...
12 votes

Labeling of high symmetry points in Brillouin zone

I think the naming conventions are standardized and people computing band structures employ them directly. I will break down the high-symmetry points for a 2-D brillouin zone and post very good ...
  • 2,212
12 votes

Is there an energy gap correction factor that needs to be used in DFT calculations?

I would like to add a few clarifications to Jack's answer: Standard DFT calculations with fixed ionic positions are actually not even 0 K. A better way to describe them is that they are static ...
  • 10.4k
11 votes

Is there an energy gap correction factor that needs to be used in DFT calculations?

Is this calculated indirect bandgap at room temp. or at 0K? QE is based on the density functional theory (DFT). DFT is a ground-state (0K) theory and hence the calculated bandstructure is 0K. If it ...
  • 14k
11 votes
Accepted

conceptual problem about the energy band along the High symmetry point in the Brillouin zone

I will try to outline this in simple terms. There are certainly more rigorous explanations. The high-symmetry points in the Brillouin zone are those that remain physically identical when certain ...
  • 856
11 votes
Accepted

Number of KPOINTS in irreducible part of Brillouin zone

It is not necessary to care about the total energy versus the number of k points in irreducible reciprocal space, which is closely related to the symmetry of the investigated structure. Of course, you ...
  • 14k
7 votes

Brillouin zone integration and delta function

I think in this case one should realize what the imaginary constant $i\eta$ stands for. Ideally this is a non-physical constant that is used to remove the possibility of hitting the singular point $\...
  • 1,814
7 votes
Accepted

How to find which atoms/bonds contribute to the particular section of band structure?

You can calculate an orbital projected density of states and band structure to see what atomic states correspond to features in the DOS and band structure. That’s one of the things that they plot in ...
  • 729
6 votes

How to generate the high symmetry paths for band structure calculations?

Pymatgen can definitely do what you are asking for. You can find several algorithms under the pymatgen.symmetry.kpath module here. I include a minimal example below ...
  • 6,941
6 votes
Accepted

How could I fold a specific high symmetry point to the Gamma point?

Setup. Consider a primitive cell with lattice vectors $\mathbf{a}_{p_1}$, $\mathbf{a}_{p_2}$, and $\mathbf{a}_{p_3}$. You can construct a supercell with lattice vectors $\mathbf{a}_{s_1}$, $\mathbf{a}...
  • 10.4k
6 votes

k-points: Odd vs. Even

The reason why even number k-point grids are prefered in the case of some symmetries like FCC lattices is mainly due to the concept of the Irreducible Brillouin Zone (IBZ). Here is an example for FCC: ...
  • 4,278
5 votes

2D Brillouin zone generator

I didn't notice this before, but the link provided in the question can already be used to visualize any 2D Brillouin zone. Since you can define the ratio of b/a, and the angle between b and a, then ...
  • 2,931
5 votes
Accepted

Generating a Gamma centered uniform k mesh in SIESTA DFT

The siesta kgrid specification looks like this: ...
  • 1,814
4 votes

Translating fractional coordinates resulting from conventional cell and primitive cell

I've never done this before but here is my guess of how you can do it. If the numbers you posted are the unit cell axes vectors with a vector for each column then their direct matrices are. $$\tag{1}\...
  • 341
3 votes

Brillouin zone integration and delta function

The short answer is No. From your Eq.(1) to Eq.(2), the following identity is used: \begin{align}\tag{1} \dfrac{1}{x-i\eta} = \dfrac{x+i\eta}{x^2+\eta^2}=\dfrac{P}{x}+i\pi\delta(x) \end{align} where $...
  • 14k
3 votes

Calculating the band structure with different unit cell

The electronic band structure is a concept for periodic system. Heterostructures are not periodic system (in the direction of heterostructure grow). What is done is an approximation where the bulk's ...
  • 19.3k
3 votes

Calculating the band structure of Bi2Se3 with spin-orbit coupling

Here are some possible changes to your input that may resolve the problem: Your EDIFF is very small; use the default and then increase precision from there. Use a ...
3 votes

How to generate the high symmetry paths for band structure calculations?

Here are a couple of extra links that might be helpful in your (now 5months old) quest: [1], [2]. It would be helpful for all of us if you could put up that green chekmarck on the answers you found ...
  • 1,266
3 votes

How to choose half-Brillouin-zone (HBZ) in Fukui & Hatsugai's numerical scheme for the Z2 invariant?

I think I figured this out. For most practical purposes, I think it is fine to just choose $-\pi\leq k_x\leq \pi$ and $0\leq k_y\leq \pi$ (half-BZ, with exact ranges depending on the model). I think ...
3 votes

Translating fractional coordinates resulting from conventional cell and primitive cell

Background. Let $(\mathbf{a}_{p_1},\mathbf{a}_{p_2},\mathbf{a}_{p_3})$ be your primitive cell lattice vectors, and let $(\mathbf{a}_{s_1},\mathbf{a}_{s_2},\mathbf{a}_{s_3})$ be your supercell lattice ...
  • 10.4k
1 vote

Calculating the band structure with different unit cell

I think Camps gives a mostly correct answer for this. I will say though, it may be possible in some cases to generate a band structure in the direction of the heterostructure by making a periodic ...

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