# Crystalline boron : computation of the total energy
#

#Definition of the unit cell
acell 3*1 Angstrom     # This is equivalent to   10.18 10.18 10.18
rprim 2.4537500000 1.4166732230 4.1863333333
-2.4537500000 1.4166732230 4.1863333333
0.0000000000 -2.8333464460 4.1863333333


#Definition of the atom types
ntypat 1          # There is only one type of atom
znucl  5          # 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  12         # There are two atoms
typat  12*1       # They both are of type 1, that is, Silicon.
xred              # This keyword indicate that the location of the atoms
  0.0101400000  -0.3466200000   0.0101400000
  0.0101400000   0.0101400000  -0.3466200000
 -0.3466200000   0.0101400000   0.0101400000
  0.3466200000  -0.0101400000  -0.0101400000
 -0.0101400000  -0.0101400000   0.3466200000
 -0.0101400000   0.3466200000  -0.0101400000
  0.2211400000  -0.3694400000   0.2211400000
  0.2211400000   0.2211400000  -0.3694400000
 -0.3694400000   0.2211400000   0.2211400000
  0.3694400000  -0.2211400000  -0.2211400000
 -0.2211400000  -0.2211400000   0.3694400000
 -0.2211400000   0.3694400000  -0.2211400000


#Definition of the planewave basis set
ecut  8.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetry
ngkpt 2 2 2       # This is a 2x2x2 grid based on the primitive vectors
nshiftk 4         # of the reciprocal space (that form a BCC lattice !),
                  # repeated four times, with different shifts :
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5
                  # In cartesian coordinates, this grid is simple cubic, and
                  # actually corresponds to the
                  # so-called 4x4x4 Monkhorst-Pack grid

#Definition of the SCF procedure
nstep 10          # 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 12.0       # 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.
