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--- exercises:2017_uzh_cmest:band [2017/10/17 10:37] – jglan
+++ exercises:2017_uzh_cmest:band [2020/08/21 10:15] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-======= Getting the band structure of graphene =======
+======= Getting the band structure of WO$_3$ Lattice =======
+In this exercise, you will carry out band structure calculation using K-point sampling for Cubic lattice WO$_3$. The reference band structure you can find in [[http://pubs.acs.org/doi/abs/10.1021/cm3032225|this paper]]
+{{:exercises:2017_uzh_cmest:wo3.jpeg?1200|}}
 To get the band structure for WO3, only a few changes are required compared to the previous example for [[PDOS|calculating the PDOS]]:
@@ Line 62: / Line 66: @@
             &KPOINT_SET
                UNITS B_VECTOR
-               SPECIAL_POINT ???   #gama
+               SPECIAL_POINT ???   #GAMA
                SPECIAL_POINT ???   #X
                SPECIAL_POINT ???   #M
                SPECIAL_POINT ???   #GAMA
-               SPECIAL_POINT ???   #r
+               SPECIAL_POINT ???   #R
                SPECIAL_POINT ???   #M
-               NPOINTS 5
+               NPOINTS ???
             &END
          &END BAND_STRUCTURE
@@ Line 111: / Line 115: @@
   * 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.
-  * 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/PRINT/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 ''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//.
-Now, when you run this input file you will get in addition the the output file, a file named ''graphene.bs'' which will look similar to the following:
+Now, when you run this input file you will get in addition the the output file, a file named ''WO3.bs'' which will look similar to the following:
 <code>
- SET:       1                 TOTAL POINTS:      6
+ SET:       1                 TOTAL POINTS:      26
-   POINT   1                     0.000000    0.000000    0.000000
+   POINT   1                     ********    ********    ********
-   POINT   2                     0.500000    0.000000    0.000000
+   POINT   2                     ********    ********    ********
+   POINT   3                     ********    ********    ********
+   POINT   4                     ********    ********    ********
+   POINT   5                     ********    ********    ********
+   POINT   6                     ********    ********    ********
        Nr.    1    Spin 1        K-Point  0.00000000  0.00000000  0.00000000
-           -15.30752034     -3.31285773      0.93143545      1.03651421
+           -73.66652408    -38.53370023    -37.80464132    -37.79327769
-.71874068     12.74920179     12.83785311     15.50144316
+           -16.71308703    -16.11075946    -16.02553853     -1.43495530
-       Nr.    2    Spin 1        K-Point  0.02500000  0.00000000  0.00000000
+            -1.34739188     -1.33357408      0.37912017      0.38948689
+.39582882      0.40030859      0.46965212      0.47418816
-           -15.29453364     -3.29547462      0.87472486      1.00321991
+.60728842      2.62105342      3.16044140      6.99806305
-.31998068     12.81500348     12.93001933     15.45108207
+       Nr.    2    Spin 1        K-Point  0.00000000  0.10000000  0.00000000
-       Nr.    3    Spin 1        K-Point  0.05000000  0.00000000  0.00000000
+           -73.66647294    -38.53337818    -37.80859042    -37.79536623
+           -16.67479677    -16.09554462    -15.96731960     -1.68492873
+            -1.44087258     -1.34318045      0.09257368      0.13769271
+.21643888      0.38447849      0.44179002      0.45757924
+.61768501      3.02368022      3.51828287      7.06644645
 [...]
 </code>
@@ Line 137: / Line 151: @@
 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. Choose an appropriate number of interpolation points to get a smooth plot.
+  * Lookup the special points for the $\Gamma$, $X$,$M$,$R$ points in the [[http://pubs.acs.org/doi/abs/10.1021/cm3032225|mentioned paper]] (make sure you choose the right lattice). Calculate and plot the band structure for WO3 lattice along $\Gamma$, $X$,$M$,$\Gamma$,$R$,$M$ (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?
-  * Why do you get 8 orbital energies? Try to change the input to get more unoccupied orbitals.
+  * How many orbital energies do you get and why? 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 ''cp2k_bs2csv.py'' from below, 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 plotted directly, you can use the script ''cp2k_bs2csv.py'' from below, which when passed a band structure file ''WO3.bs'' as an argument will write files ''WO3.bs-set-1.csv'' for each set containing the K-Point coordinates and the energies in one line.
+To plot the ''WO3.bs-set-1.csv'' file, you can either load it into $MATLAB$ or use $GNUPLOT$ command line.
+<code>gnuplot>set yrange [-8:14]
+gnuplot>plot for [i=4:23] "WO3.bs.set-1.csv" u 0:i w l t ""
+ </code>
 <file python cp2k_bs2csv.py>
 #!/usr/bin/env python