Questions tagged [k-points]
Questions regarding k-points in crystal geometric settings.
22
questions
7
votes
1answer
141 views
Number of KPOINTS in irreducible part of Brillouin zone
I want to investigate the comparison of Total Energy per cell with respect to the number of KPOINTS in irreducible part of Brillouin zone but I do not know how to calculate the number of KPOINTS with ...
6
votes
2answers
44 views
Does SOC band structure calculations require higher number of k-grids?
In so many papers I see that they carry out soc band structure calculations with much higher kgrid than used for the geometry optimization. Whats the logic behind that?
3
votes
2answers
89 views
Energy per unit cell in NWChem differs for different supercells despite the same k-points density
I try to compute the unit cell energy of the $\ce{Ti2CO2}$ MXene with NWchem.
Computing the 1x1 supercell with 4x4x1 K-points grid I got -1875 Ha.
Computing the 2x2 supercell with 2x2x1 K-points grid ...
8
votes
1answer
77 views
How to analyze the band symmetry with Quantum ESPRESSO?
This question is related to this paper: J. Phys. Chem. Lett. 2017, 8, 13, 2999–3007
The above figure shows symmetry analysis for the band structure. The author writes:
The band symmetry and parity ...
9
votes
2answers
89 views
Validity of interpolation for density of states?
A density of states (DoS) curve seems like an example of a curve for which curve fitting doesn't seem to make sense, or does it? How could we interpolate on such a curve, given that we got the curve ...
13
votes
1answer
174 views
Is total energy difference lower than 1 meV/atom good enough for k-point convergence?
How much energy difference could be considered as tight convergence? Is total energy difference lower than 1 meV/atom good enough for kpoint convergence for total energy calculation?
7
votes
1answer
163 views
k-points: Odd vs. Even
As mysterious as k-points are, why is there a cut-off for an odd and even k-mesh preference?
On the VASP wiki page titled, "Number of k points and method for smearing", they say results when ...
10
votes
5answers
829 views
How to know optimal K-points grid values for good DFT calculation?
I am doing DFT calculations with pw.x executable in Quantum Espresso. For this we have to choose right K-points grid in order to perform error-less calculation. But I have no idea about how can I ...
9
votes
1answer
141 views
Monkhorst-Pack, Gamma-centred and gamma only
Sorry if this question is too simple for this community but I still couldn't find an answer to it.
Do gamma-centred and gamma only grid mean the same thing?
If not, what's the difference?
How do they ...
11
votes
1answer
78 views
adaptive k-mesh
Are there any known codes or scripts to generate an adaptive k-mesh for DFT calculations? For example, I'd like to make the k-mesh near the $\Gamma$ point (e.g., half the zone) more denser ($20\...
7
votes
2answers
67 views
Input constraints while comparing different DFT calculated properties for the same material but different atomic arrangement
Let's consider a fictitious AB type binary alloy. AB is known to exist in a B2 type ordered ...
10
votes
1answer
196 views
Increasing supercell size to increase K-points sampling
Suppose I have a system with a property that is highly dependent on the density of k-points, namely the dielectric function. Using a small supercell, say with 4 atoms, I've reached the maximum allowed ...
11
votes
2answers
134 views
Which properties of a material calculated using density functional theory are affected by smearing?
Smearing (smearing width $\sigma$, to be precise) has always been confusing. I understand what it is but can't pin it down when it comes to DFT calculations. Should it be converged like k-points and ...
8
votes
2answers
102 views
k-points convergence for spin polarised vs non-polarised DFT calculations
Spin-polarised calculations come at a computational cost and I tend to take ISPIN = 2 only after I'm done with a proper initial relaxation of the structure, so the ...
7
votes
0answers
164 views
Calculating band structure with HSE using Open_grid (Quantum ESPRESSO) [closed]
I have executed the SCF calculation and obtained the results. After which I used kmesh.pl to extract k-points. I was able to run wannier calculations but there was an error
Checking info from wannier....
13
votes
2answers
374 views
mBJ-LDA band structure calculation using VASP
I tried to create a band structure for mBJ-LDA using VASP. I found information that the KPOINTS file should be created according to the "0-weight (Fake) SC procedure" (as for HSE)
I have a ...
8
votes
3answers
496 views
How to generate KPOINTS file for HSE06 band-structure calculations?
I have had a look at the example of Silicon provided here
in the WIKIVASP website, and I noticed that the KPOINTS file used for ...
10
votes
1answer
166 views
Is it okay to take a cubic Monkhorst-Pack k-mesh for a non-cubic supercell in a DFT calculation?
Assume that the numbers of k-points in each direction are sufficient.
Example - Lengths of lattice vectors: $2\: 2\: 4$
Required k-mesh: $9\times 9\times 5$
Would a $9\times 9\times 9$ k-mesh work? ...
9
votes
1answer
186 views
How to derive the k-path for monoclinic lattice structure?
Good afternoon all,
My post is inquiring about the mathematical derivation behind the Monoclinic crystal structure (c axis unique).
The Brillouin zone (BZ) I really would like to derive is shown below:...
12
votes
4answers
360 views
How to make a k-point convergence test for a bulk structure with a lower k-point in the z-direction?
Let's say I want to make k-point convergence test for graphite. And let's say it converges at 12x12x4.
Do I first need to do a k-point convergence test for equal k-points on xyz directions then make ...
14
votes
3answers
507 views
Running Quantum ESPRESSO calculations in Google Colab
So one big problem I experience in doing calculations with Quantum ESPRESSO is that many calculations require a lot of computing power: you need large RAM capacities and powerful processors especially ...
16
votes
1answer
101 views
k-points convergence for special quasirandom structures (SQS) of the same material containing different # of atoms
For an ordered crystal, we generally converge the k-mesh resolution for a primitive cell or other smaller supercells. We then use this resolution for any other size of the supercell for the same ...
