#    * Born effective charges

   ndtset   3

# Set 1 : Initial self-consistent run

    iscf1   5
  kptopt1   1
  tolvrs1   1.0d-18  #need excellent convergence of GS quantities for RF runs


# Set 2 : Calculate the ddk wf's - needed for piezoelectric tensor and 
#         Born effective charges in dataset 3

  getwfk2  -1
    iscf2  -3        #this option is needed for ddk
  kptopt2   2        #use time-reversal symmetry only for k points
    nqpt2   1        #one wave vector will be specified
     qpt2   0 0 0    #need to specify gamma point
  rfelfd2   2        #set for ddk wf's only
   rfdir2   1 1 1    #full set of directions needed
  tolwfr2   1.0d-20  #only wf convergence can be monitored here

# Set 3 : response-function calculations for all needed perturbations

  getddk3  -1
  getwfk3  -2
    iscf3   5
  kptopt3   2        #use time-reversal symmetry only for k points
    nqpt3   1
     qpt3   0 0 0
  rfphon3   1        #do atomic displacement perturbation
 rfatpol3   1 4      #do for all atoms
  rfstrs3   3        #do strain perturbation
   rfdir3   1 1 1    #the full set of directions is needed
  tolvrs3   1.0d-10  #need reasonable convergence of 1st-order quantities
  #Common input variables
#Total enrgy of CuInSe (I42d group)
#Definition of the unit cell
acell 3*7.692047091691874      # This is equivalent to   10.61 10.61 10.61
rprim  1.0  0.0  0.0   # In lessons 1 and 2, these primitive vectors 
       0.0  1.0  0.0   # (to be scaled by acell) were 1 0 0  0 1 0  0 0 1 
       0.5  0.5  0.9329012766836911  # that is, the default.

#Definition of the atom types
ntypat 3               # There are two types of atom
znucl 13 5 7            # The keyword "znucl" refers to the atomic number of the 
                       # possible type(s) of atom. The pseudopotential(s) 
                       # mentioned in the "files" file must correspond
                       # to the type(s) of atom. Here, type 1 is the Aluminum,
                       # type 2 is the Arsenic.

#Definition of the atoms
natom 8                # There are two atoms
typat 1 1 2 2 3 3 3 3             # The first is of type 1 (Al), the second is of type 2 (As).
xred                   # This keyword indicate that the location of the atoms
                       # will follow, one triplet of number for each atom
  


              6.9388939039E-18 -2.0816681712E-17 -1.3877787808E-17
             -2.5000000000E-01  2.5000000000E-01  5.0000000000E-01
              5.0000000000E-01  5.0000000000E-01 -1.3877787808E-17
              2.5000000000E-01 -2.5000000000E-01  5.0000000000E-01
              1.8173101317E-01  1.2500000000E-01  2.5000000000E-01
             -4.3173101317E-01 -3.7500000000E-01  2.5000000000E-01
             -1.2500000000E-01  4.3173101317E-01 -2.5000000000E-01
              3.7500000000E-01 -1.8173101317E-01 -2.5000000000E-01


#Gives the number of band, explicitely (do not take the default)
#nband  16               # For an insulator (if described correctly as an insulator 
                       # by DFT), there is no need to include conduction bands 
                       # in response-function calculations

#Exchange-correlation functional
ixc 1             # LDA Teter Pade parametrization

#Definition of the planewave basis set
ecut   5.0               # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
#kptrlatt -4  4  4      # In cartesian coordinates, this grid is simple cubic, and
 #         4 -4  4      # actually corresponds to the so-called 8x8x8 Monkhorst-Pack grid.
  #        4  4 -4      # It might as well be obtained through the use of
   

                    # ngkpt, nshiftk and shiftk .
kptopt 1
#nkptopt 1
nshiftk 1

shiftk  
0.50 0.50 0.50
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0  0.5
ngkpt  4 4 3
#Definition of the SCF procedure
nstep 150               # Maximal number of SCF cycles
diemac 9.0             # Although this is not mandatory, it is worth to
#toldfe 1.0d-6
                       # precondition the SCF cycle. The model dielectric
                       # function used as the standard preconditioner
                       # is described in the "dielng" input variable section.
                       # The dielectric constant of AlAs is smaller that the one of Si (=12).