#!/bin/bash

export kp=32
export cut=50
export NAME=GaAs

# Compute the band structure in a large grid
# It is also possible to use a small enough grid for 
# scf, and a large grid for nscf. 

cat > GaAs.scf.in << EOF
&control
   calculation   = 'scf'
   restart_mode  = 'from_scratch'
   prefix        = '$NAME'
   pseudo_dir    = '.'
   outdir        = '.'
   verbosity     = 'high'
   etot_conv_thr = 1.d-5
   forc_conv_thr = 1.d-4
/
&system
   ibrav = 2, 
   celldm(1) = 10.6867, 
   nat = 2, 
   ntyp = 2,
   ecutwfc = $cut,
   ecutrho = $[12*$cut],
   nspin = 1
   nbnd  = 16 
   la2F  = .true. 
/
&electrons
   mixing_beta      = 0.3 
   conv_thr         = 1.0d-8
   electron_maxstep = 200,
/
&ions
/
&cell
  press = 0.0
/
ATOMIC_SPECIES
   Ga  69.723    Ga.pbe-dn-kjpaw_psl.0.2.upf 
   As  74.921595 As.pbe-n-kjpaw_psl.0.2.upf
ATOMIC_POSITIONS
 Ga  0.00 0.00 0.00
 As  0.25 0.25 0.25
K_POINTS {automatic}
   $kp $kp $kp 0 0 0
EOF

./pw.x < GaAs.scf.in > GaAs.scf.out

mv GaAs.a2Fsave GaAs.$kp.a2Fsave