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exercises:2016_uzh_cmest:band_structure_calculation [2016/11/06 15:04] – tmuellerexercises:2016_uzh_cmest:band_structure_calculation [2016/11/06 15:06] – tmueller
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   * By specifying the ''KPOINT'' section you are enabling the K-Point calculation.   * By specifying the ''KPOINT'' section you are enabling the K-Point calculation.
   * While you could specify the K-Points directly, we are using the Monkhorst-Pack scheme [(http://journals.aps.org/prb/abstract/10.1103/PhysRevB.13.5188)] to generate them. The numbers following the keyword ''MONKHORST-PACK'' specify the tiling of the brillouin zone.   * While you could specify the K-Points directly, we are using the Monkhorst-Pack scheme [(http://journals.aps.org/prb/abstract/10.1103/PhysRevB.13.5188)] to generate them. The numbers following the keyword ''MONKHORST-PACK'' specify the tiling of the brillouin zone.
-  * After the basic calculation, CP2K calculates the energies along certain lines, denoted as ''KPOINT_SET'' (when you check [https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/KPOINTS/BAND_STRUCTURE/KPOINT_SET.html|the documentation] you will note that this section can be repeated).+  * After the basic calculation, CP2K calculates the energies along certain lines, denoted as ''KPOINT_SET'' (when you check [[https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/KPOINTS/BAND_STRUCTURE/KPOINT_SET.html|the documentation]] you will note that this section can be repeated).
   * The keyword ''NPOINTS'' specifies how many points (in the addition to the starting point) should be sampled between two special points.   * The keyword ''NPOINTS'' specifies how many points (in the addition to the starting point) should be sampled between two special points.
   * The ''SPECIAL_POINT'' keyword is used to specify the start-, mid- and endpoints of the line. Those points usually denote special points in the reciprocal lattice/unit cell, like the $\Gamma$, $M$ or $K$ point. You can find the definition for these in the appendix section of [[http://www.sciencedirect.com/science/article/pii/S0927025610002697|this paper]]. This keyword can also be specified multiple times, making it possible to directly get the band structure for a complete //path//.   * The ''SPECIAL_POINT'' keyword is used to specify the start-, mid- and endpoints of the line. Those points usually denote special points in the reciprocal lattice/unit cell, like the $\Gamma$, $M$ or $K$ point. You can find the definition for these in the appendix section of [[http://www.sciencedirect.com/science/article/pii/S0927025610002697|this paper]]. This keyword can also be specified multiple times, making it possible to directly get the band structure for a complete //path//.
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 Your tasks: Your tasks:
  
-  * Lookup the special points for the $\Gamma$, $M$, $K$ points in the mentioned paper (make sure you choose the right lattice). Calculate and plot the band structure for graphene from $\Gamma$ over $M$, $K$ back to $\Gamma$ (you are free to decide whether to use multiple K-Point sets are multiple special points in a single set). Mark the special points.+  * Lookup the special points for the $\Gamma$, $M$, $K$ points in the mentioned paper (make sure you choose the right lattice). Calculate and plot the band structure for graphene from $\Gamma$ over $M$, $K$ back to $\Gamma$ (you are free to decide whether to use multiple K-Point sets are multiple special points in a single set). Mark the special points. Choose an appropriate number of interpolation points to get a smooth plot.
   * Compare your plot with plots from literature. What is different?   * Compare your plot with plots from literature. What is different?
   * Why do you get 8 orbital energies? Try to change the input to get more unoccupied orbitals.   * Why do you get 8 orbital energies? Try to change the input to get more unoccupied orbitals.
  
 To convert the band structure file to a file which can be loaded directly into MATLAB for example, you can use the script ''/users/tiziano/bin/cp2k_bs2csv.py'' which when passed a band structure file ''graphene.bs'' as an argument will write files ''graphene.bs-setN.csv'' for each set containing the K-Point coordinates and the energies in one line. To convert the band structure file to a file which can be loaded directly into MATLAB for example, you can use the script ''/users/tiziano/bin/cp2k_bs2csv.py'' which when passed a band structure file ''graphene.bs'' as an argument will write files ''graphene.bs-setN.csv'' for each set containing the K-Point coordinates and the energies in one line.
exercises/2016_uzh_cmest/band_structure_calculation.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1