# H2 molecule in a big box
#
# This file will optimize automatically the interatomic distance

#Define the methodology to find the minimum
ionmov  3              # Use the modified Broyden algorithm
ntime   10             # Maximum number of Broyden "timesteps"
tolmxf  5.0d-4         # Stopping criterion for the geometry optimization : when 
                       # the residual forces are less than tolmxf, the Broyden 
                       # algorithm can stop
xcart  -0.7   0.0 0.0  # The starting values of the
        0.7   0.0 0.0  # atomic coordinates

toldff  5.0d-5         # Will stop the SCF cycle when, twice in a row, 
                       # the difference between two consecutive evaluations of
                       # forces differ by less than toldff (in Hartree/Bohr)


nband    1             # Only one band is occupied. In order to get the energy,
                       # forces ..., there is no need to compute more than one band.

#-------------------------------------------------------------------------------
#The rest of this file is similar to the t11.in file, except
#that xcart has been moved above, and that toldfe has been replaced
#by toldff, see above.

#Definition of the unit cell
acell 10 10 10    # The keyword "acell" refers to the
                  # lengths of the primitive vectors (in Bohr)

#Definition of the atom types
ntypat 1          # There is only one type of atom
znucl 1           # 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 Hydrogen.
                         

#Definition of the atoms
natom 2           # There are two atoms
typat 1 1         # They both are of type 1, that is, Hydrogen

#Definition of the planewave basis set
ecut 10.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
nkpt 1            # Only one k point is needed for isolated system,
                  # taken by default to be 0.0 0.0 0.0

#Definition of the SCF procedure
nstep 10          # Maximal number of SCF cycles
#toldfe is no more defined, as toldff is used above... 
diemac 2.0        # 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 prescriptions for molecules
                  # in a big box
