# Crystalline aluminum 
#
# A first step in the determination of the surface energy of aluminum :
# changing the orientation of the cell.

#Definition of occupation numbers
occopt 4
tsmear 0.04

#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetries
ngkpt  4 4 4  
nshiftk 2
shiftk  0.5 0.0 0.5
        0.0 0.5 0.5


#Definition of the unit cell
acell 3*7.50559090E+00   # Lattice parameters of bulk aluminum
rprim  0.5 -0.5  0.0     # These values will define a cell with two atoms,
       0.5  0.5  0.0     # non-primitive, with a different orientation
       0.0  0.0  1.0     # than the primitive cell.
chkprim 0                # This input variable allows to use non-primitive unit
                         # cells. Please, do not use it in other cases,
                         # you might miss a primitive cell, faster to handle.

#Definition of the atom types
ntypat 1          # There is only one type of atom
znucl 13          # 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 Aluminum
                         

#Definition of the atoms
natom 2           # There are two atoms in this doubled cell
typat 2*1         # These atoms are of type 1, that is, Aluminum
xred              # This keyword indicate that the location of the atoms
                  # will follow, one triplet of number for each atom
   0.0  0.0  0.0     # Triplet giving the REDUCED coordinate of atom 1.
   0.5  0.5  0.5     # Triplet giving the REDUCED coordinate of atom 2.
 
#Exchange-correlation functional
ixc 1             # LDA Teter Pade parametrization

#Definition of the planewave basis set
ecut  6.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 10          # Maximal number of SCF cycles
toldfe 1.0d-6