# Crystalline Sr2CoO4 : computation of the total energy
# Convergence with respect to the number of k points.

ndtset 1

#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetry
nshiftk 1
shiftk  0.5 0.5 0.5  # These shifts will be the same for all grids

ngkpt  4 4 4     # Definition of the different grids

getwfk -1         # This is to speed up the calculation, by restarting
                  # from previous wavefunctions, transferred from the old 
                  # to the new k-points.


# Data set 3: density of states
prtdos  2

#Definition of the unit cell
acell 7.147618 7.147618 23.527618                                                     
rprim    -0.5  0.5  0.5   # primitive vectors (to be scaled by acell)
          0.5 -0.5  0.5   
          0.5  0.5 -0.5

#Definition of the atom types
ntypat 3          # There is only one type of atom
znucl 38 27 8     # 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, the only type is Silicon.
                         

#Definition of the atoms
natom 7           # There are two atoms
typat 1 1 2 3 3 3 3                                                           
xred             # This keyword indicate that the location of the atoms
                  # will follow, one triplet of number for each atom
   0.0000  0.0000  0.3591  # Triplet giving the REDUCED coordinate of atom 1.
   0.0000  0.0000  0.6409
   0.0000  0.0000  0.0000
   0.0000  0.5000  0.0000
   0.5000  0.0000  0.0000
   0.0000  0.0000  0.1596
   0.0000  0.0000  0.8404

#Definition of the planewave basis set
ecut  30.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
iprcel  45
nstep 300          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference 
                  # between two consecutive evaluations of total energy 
                  # differ by less than toldfe (in Hartree) 
diemac 10.0       # Although this is not mandatory, it is worth to
                  # precondition the SCF cycle. The model dielectric
                  # function used as the standard preconditioner
                  # is described in the "dielng" input variable section.
                  # Here, we follow the prescription for bulk silicon.