How to set k-points in a supercell band structure calculation ?

[Tianshu Jiang]

Hi developers and users in CP2K community,

I want to reproduce the result appearing in some literature, about calculating band structure of GNR (graphene nano ribbons) .

But I am confused about the settings in section &KPOINT_SET. I use tools provided by https://www.materialscloud.org/work/tools/seekpath help to identify the coordinate of

high symmetry points.

The setting of my system is as following 

  &SUBSYS

    &CELL

      ABC [angstrom] 4.2608 2.4612 10

      ALPHA_BETA_GAMMA 90. 90. 90.

      #SYMMETRY HEXAGONAL

      PERIODIC XYZ

      MULTIPLE_UNIT_CELL 6 2 1

    &END CELL

    &TOPOLOGY

      MULTIPLE_UNIT_CELL 6 2 1

    &END TOPOLOGY

    &COORD

      SCALED

      C 1./6. 1./2. 0.

      C 1./2. 1./2. 0.

    &END

But the band structure looks messy, there are too many energy levels. The plot of band structure looks 

I want to know how to extract useful energy levels and reproduce the results in literature.

Thanks for all your suggestion.

[Tiziano Müller]

Hi Tianshu,

The reason for the "messy" bandstructure is likely due to zone folding
due to the use of a supercell/non-primitive unit cell.

Futhermore, make sure that you use CP2K version 5.1 or newer since CP2K
4.1 had a bug wrt the units for the special points vectors.

Best regards,
Tiziano

> gnr.png
>
>
> I want to know how to extract useful energy levels and reproduce the
> results in literature.
> Thanks for all your suggestion.
>
>
>
>

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--
Tiziano Müller
University of Zurich
Department of Chemistry
Winterthurerstrasse 190
CH-8057 Zürich

Tel: +41 44 63 54234
www.chem.uzh.ch
tiziano...@chem.uzh.ch

[Tianshu Jiang]

Hi Müller, 

the program I am using is cp2k 4.1, I will reinstall newer version to test my system.

By the way, what key words should I added to the input file if I want to do a non-primitive calculation ?

Or there is some tutorial to refer ? And how should I deal with the data for plotting to get a fig compared to those in literature? 

I have been using the script cp2k_bs2csv.py and another python script written by myself to plot the fig. 

I major in computational mathematic, therefore, maybe I have no such clear 

insight into the calculation in solid physics and computational chemistry.

Thanks for your patience !

在 2019年4月15日星期一 UTC+8下午5:32:44，Tiziano Müller写道：

> an email to cp...@googlegroups.com
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