[QE-users] Band structure calculation

[Giovanni Cantele]

Hi,
it is always a good practice to look at the documentation first.

Here, you can find some answers to your questions:
https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm1487

nks:  Number of supplied special k-points.
So, you decide how many points you want in your path (e.g., 50) and fix nks
to that value.

How to write the k-point path: given that your crystal is 1D, this is
an easy task. As you might read from the above link,
you specify the units of supplied k-points after K_POINTS. Let's use
'crystal' units and let us suppose that the direction of periodicity
of your crystal is the x one.
Your path (in crystal units) begins from -0.5 0.0 0.0 and ends to 0.5 0.0
0.0. As an example you can specify
K_POINTS { crystal }
11
-0.5  0.0  0.0.   1.0
-0.4  0.0  0.0.   1.0
-0.3  0.0  0.0.   1.0
-0.2  0.0  0.0.   1.0
-0.1  0.0  0.0.   1.0
 0.0  0.0  0.0.   1.0
 0.1  0.0  0.0.   1.0
 0.2  0.0  0.0.   1.0
 0.3  0.0  0.0.   1.0
 0.4  0.0  0.0.   1.0
 0.5  0.0  0.0.   1.0

A smooth band structure plot would require a finer division of the [-0.5
0.0 0.0] - [0.5 0.0 0.0] segment.
The fourth column (that with all the "1.0") contains k-points weights that
would be suitably set in the self-consistent calculation, but they do not
affect the results in a band structure not self consistent calculation (and
can be set to any value).

Giovanni
-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it <giovanni.cantele at spin.cnr.it>
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home


Il giorno dom 25 dic 2022 alle ore 17:23 Rameswar Bhattacharjee <
rb1820 at georgetown.edu> ha scritto:

> Hi Everyone,
> I am trying to do a band structure calculation of a 1D organic crystal.
> The path of the band should be   * -pi/a-gamma-pi/a*  as used in the
> previous literature. Can anyone tell me how to write the k-path from -pi/a
> to +pi/a via gamma point in the QE input? Also, how to choose the "nks"
> value for each k-points coordinate.
>
> Any suggestion would be highly appreciated. I am attaching an image from a
> previous literature for a sample reference. Thank you in advance and Merry
> Christmas to all!!!!
>
> Rameswar Bhattacharjee
> Georgetown University
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