[Pw_forum] Kpoints-generation

[Giovanni Cantele]

On Oct 25, 2013, at 9:10 AM, paresh rout <paresh.rout88 at gmail.com> wrote:

> Dear all,
>            I want to generate K-point grid for band structure calculation by using kpoints.x in espresso. But I do not know what will be its in put file and its required parameters.Any help will be highly appreciated.
> 
> Best regards
> Paresh Chandra Rout
> IISER BHOPAL
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If I well understand,
I think that what you are looking for is not a k-point grid (for which kpoints.x would be an helpful tool), but a k-point path
within the 1st Brillouin zone to show a band structure.

To this purpose, after self-consistency, you can run pw.x after setting
calculation = 'bands'
and specifying the K_POINTS card as follows (see PW/Doc/INPUT_PW.txt):

K_POINTS {crystal_b}
nks
            xk_x(1)    xk_y(1)    xk_z(1)    wk(1)
            xk_x(2)    xk_y(2)    xk_z(2)    wk(2)
            . . .
            xk_x(nks)  xk_y(nks)  xk_z(nks)  wk(nks)
where nks points specify nks-1 lines in reciprocal space.
Every couple of points identifies the initial and final point of a line. pw.x generates N
intermediate points of the line where N is the weight of the first point.


The intermediate points choice depends on your crystal structure and on what special lines
in the Brillouin zone you are interested in.
You might refer to specialised textbooks or search the web for special points coordinates
(for example here you find BZ plots and special points coordinates, once you know the space
group: http://www.cryst.ehu.es/cryst/get_kvec.html).

Giovanni

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Giovanni Cantele, PhD
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