I am not sure what you want to tdo ? Did you want just to plot a bandstructure than you have to do use task 20 for a band structure plot and specify the band plot ''lines''. This you do by providing the points you want to connect by a line: see for example the case provided in the
examples/basic/AlAs-fatbands/
where plot specifies first three points connected by 200 kpoints each and below the coordinates of the three points in reciprocal space
Hello sir,
I used "autokpt=.true." in Si example and I found that there are 4913 k-points. I want to know that how many bands can be calculated and what are the commands. Can we control the numbers of k-points and number of bands than?
Thank you
With Regards
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I don't think any of us quite understand what your goal is, and it is therefore difficult to help. I assumed that you are trying to plot the band structure of some compound with labelled k-points and a larger range of energies than usual. I hope it helps.
There are a few things you need to consider when using elk-bands.
1) Does the elk simulation have enough bands to cover the energy range you care about. As Michael mentioned, this is controlled by nempty. The default is probably ok for your purpose.
2) Are there enough k-points in the simulation to make the bands smooth. (with autokpt=true, there are almost certainly enough)
3) What special points do you want to plot? (K,Gamma,L etc) In the Si example, there are 7 special points, labelled "0 0 1", "0.5 0.5 0" etc these are the points in the brillouin zone. (See for example https://en.wikipedia.org/wiki/Brillouin_zone . The FCC cell is the first one they talk about, and they call the special points "critical points". ) I have labelled some of the points in the example below. At the bottom of the wikipedia page you will find an image labelled "Face Centered Cubic Lattice (FCC) BZ" which will help you identify the other points (Note the symmetries. And that the Brillouin zone repeats 0,0,0=0,0,1=0,0,2. Also, the book "Ashcroft/Mermin: Solid State Physics" will help.)
4) The number of points in the plot is 200 which is plenty.
5) The energy range in the plot. This is controlled by elk-bands. For example elk-bands -12 12
will give you a band structure with a broader range of energies.
6) The labels "L" "X" "Gamma" must be in the elk.in file, as I have shown below. elk-bands reads them from here.
Good luck,
Marty
!--------------------- CUT HERE ----------------------
! Band structure of silicon. The points listed after plot1d below are the
! vertices joined in the band structure.
! These are the vertices to be joined for the band structure plot
! 7=Number of Special Points
! 200=Number of interpolated k-points used to calculate the energy for the bands.
plot1d
7 200 : nvp1d, npp1d
0.0 0.0 1.0 ~G : vlvp1d
0.5 0.5 1.0 a
0.0 0.0 0.0 ~G
0.5 0.0 0.0 L
0.5 0.5 0.0 b
0.5 0.25 -0.25 c
0.5 0.0 0.0 L
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Dear sir,
Can you tell me how to generate k-points in form of kx,ky,kz for elk-bands.
Thank you
with Regards
Dear Vj,
you may consider the bandstructure examples provided with elk, which shows how to define this
best regards
Michael
Thank you very much Sir, but I want to increse the numbers of k-points & bands, and I don't know how to do it. Please guide me.
Thank you
With Regards
Dear Vj,
I am not sure what you want to tdo ? Did you want just to plot a bandstructure than you have to do use task 20 for a band structure plot and specify the band plot ''lines''. This you do by providing the points you want to connect by a line: see for example the case provided in the
examples/basic/AlAs-fatbands/
where plot specifies first three points connected by 200 kpoints each and below the coordinates of the three points in reciprocal space
plot1d
3 200 : nvp1d, npp1d
0.5 0.0 0.0 : vlvp1d
0.0 0.0 0.0
0.5 0.5 0.0
best regards
Michael
PS: If you want to increase the number of bands this is done by increasing the nempty paramenter.
Hello sir,
I used "autokpt=.true." in Si example and I found that there are 4913 k-points. I want to know that how many bands can be calculated and what are the commands. Can we control the numbers of k-points and number of bands than?
Thank you
With Regards
Hi Vijay,
I don't think any of us quite understand what your goal is, and it is therefore difficult to help. I assumed that you are trying to plot the band structure of some compound with labelled k-points and a larger range of energies than usual. I hope it helps.
There are a few things you need to consider when using elk-bands.
1) Does the elk simulation have enough bands to cover the energy range you care about. As Michael mentioned, this is controlled by nempty. The default is probably ok for your purpose.
2) Are there enough k-points in the simulation to make the bands smooth. (with autokpt=true, there are almost certainly enough)
3) What special points do you want to plot? (K,Gamma,L etc) In the Si example, there are 7 special points, labelled "0 0 1", "0.5 0.5 0" etc these are the points in the brillouin zone. (See for example https://en.wikipedia.org/wiki/Brillouin_zone . The FCC cell is the first one they talk about, and they call the special points "critical points". ) I have labelled some of the points in the example below. At the bottom of the wikipedia page you will find an image labelled "Face Centered Cubic Lattice (FCC) BZ" which will help you identify the other points (Note the symmetries. And that the Brillouin zone repeats 0,0,0=0,0,1=0,0,2. Also, the book "Ashcroft/Mermin: Solid State Physics" will help.)
4) The number of points in the plot is 200 which is plenty.
5) The energy range in the plot. This is controlled by elk-bands. For example
elk-bands -12 12
will give you a band structure with a broader range of energies.
6) The labels "L" "X" "Gamma" must be in the elk.in file, as I have shown below. elk-bands reads them from here.
Good luck,
Marty
!--------------------- CUT HERE ----------------------
! Band structure of silicon. The points listed after plot1d below are the
! vertices joined in the band structure.
tasks
0
20
! use Broyden mixing
mixtype
3
avec
5.13 5.13 0.00
5.13 0.00 5.13
0.00 5.13 5.13
sppath
'../../../species/'
atoms
1 : nspecies
'Si.in' : spfname
2 : natoms; atposl below
0.0 0.0 0.0
0.25 0.25 0.25
ngridk
2 2 2
vkloff
0.25 0.5 0.625
! These are the vertices to be joined for the band structure plot
! 7=Number of Special Points
! 200=Number of interpolated k-points used to calculate the energy for the bands.
plot1d
7 200 : nvp1d, npp1d
0.0 0.0 1.0 ~G : vlvp1d
0.5 0.5 1.0 a
0.0 0.0 0.0 ~G
0.5 0.0 0.0 L
0.5 0.5 0.0 b
0.5 0.25 -0.25 c
0.5 0.0 0.0 L
Thank you,
it helped me alot.
With Regards
vijay