====== HSE bandsctructure calculation ======

HSE bandstructure calculation for AsGa

===== Input files =====

atom.config

<code bash>
        2
 LATTICE
      0.00000000     2.71535000     2.71535000
      2.71535000     0.00000000     2.71535000
      2.71535000     2.71535000     0.00000000
 POSITION
  14     0.00000000     0.00000000     0.00000000 0 0 0
  14     0.25000000     0.25000000     0.25000000 0 0 0
</code>

etot.input

<code bash>
   4 1
   JOB = NONSCF
   IN.PSP1 = Ga.SG15.PBE.UPF
   IN.PSP2 = As.SG15.PBE.UPF
   IN.ATOM = atom.config
   XCFUNCTIONAL = HSE
   IN.VR = T
   IN.KPT = T
</code>

<WRAP round info>
  - Read IN.VR from previous SCF calculation. To copy OUT.VR, OUT.FERMI and OUT.HSEWR* from the HSE SCF calculation of example [[HSEscf.md|GaAs HSE SCF calculation]] to your current working drectory and rename IN.VR. 
  - IN.KPT is the k-points file which PWmat will use for band structure calculation, one can use “split_kp.x” utility to get it. You should prepare an input file for “split_kp.x”, which can be named “gen.kpt”:

<code bash>
      BAND                    # COMMENT line
  10                      # number of k-points between X and R
  0.500  0.000  0.000  X  # reciprocal coordinates; label 'X' for X point
  0.500  0.500  0.500  R
  10
  0.500  0.500  0.500  R
  0.500  0.500  0.000  M
  10
  0.500  0.500  0.000  M
  0.000  0.000  0.000  G
  10
  0.000  0.000  0.000  G
  0.500  0.500  0.500  R
</code>

<code bash>
      split_kp.x gen.kpt
</code>

After running "`split_kp.x gen.kpt`", it will generate "`IN.KPT`" and "`HIGH_SYMMETRY_POINT`" (high-symmetry points information) files.  

</WRAP>

As.SG15.PBE.UPF, Ga.SG15.PBE.UPF

<wrap tip> As.SG15.PEB.UPF and Ga.SG15.PBE.UPF are the pseudopotential files. </wrap>

===== Calculations =====

  - You can submit PWmat tasks in different ways:

<code bash>
   mpirun -np 4 PWmat | tee output
</code>

<wrap tip> Run the command directly </wrap>

<code bash>
   #!/bin/bash
   #PBS -N SCF
   #PBS -l nodes=1:ppn=4
   #PBS -q batch
   #PBS -l walltime=100:00:00

   ulimit -s unlimited
   cd $PBS_O_WORKDIR

   mpirun -np 4 PWmat | tee output
</code>

<wrap tip> Submit the task with a pbs script </wrap>

  - After NONSCF calculation, you can run “''%%plot_band_structure.x%%''” to obtain band structure in your current working directory. Then it will generate the following files: bandstructure.eps, bandstructure.png, bandstructure.pdf and bandstructure_1.txt (the data file of band structure), which can be used to plot band by //origin// or //gnuplot//. Note, for “spin=2”, another data file bandstructure_2.txt will be generated.

<code bash>
   plot_band_structure.x
</code>

{{:pwmat:demo:bandstructure_gaas.png| band}}