dfpt.abi

# Diamond: computation of the phonon spectrum

   iomode   3
   ndtset   3

# Q vectors for all datasets

# Complete set of symmetry-inequivalent qpt chosen to be commensurate
# with kpt mesh so that only one set of GS wave functions is needed.

   nqpt   1            # One qpt for each dataset (only 0 or 1 allowed)
   qptopt 1            # activate determining qpts in IBZ with symmetry
   ngqpt  2 2 2        # these variables mirror those used for the kpt
   nshiftq 1           # mesh below, but with no shift. In this way,
   shiftq 0 0 0        # qpts coherent with the kpts are constructed
                       # the number of resulting q pts is pretdetermined
                       # through use of the abitk tool

   iqpt: 1 iqpt+ 1     # we automatically iterate through the q pts


# Sets 1-3 : Finite-wave-vector phonon calculations (defaults for all datasets)

   getwfk_filepath "groundstateo_WFK.nc" # Use GS wave functions
   kptopt   3          # Need full k-point set for finite-Q response
   rfphon   1          # Do phonon response
   tolvrs   1.0d-18    # Converge on potential residual

# turn off various file outputs, here we will be interested only the
# DDB files

   prtwf 0
   prtden 1   # Required by GWPT
   prtpot 1   # Reqquire by EPH
   prteig 0

#######################################################################
# Common input variables

# Definition of the unit cell: fcc
    acell  3*6.751         # Experimental lattice constants
    rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)
           0.5  0.0  0.5
           0.5  0.5  0.0

# Definition of the atom types
   ntypat   1         # There are two types of atom
    znucl   6         # 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.

# Definition of the atoms
    natom   2         # There are two atoms
    typat   1 1

     xred   0.0  0.0  0.0
            0.25 0.25 0.25

# Gives the number of band, explicitly (do not take the default)
    nband   8

# Definition of the planewave basis set
     ecut   45.0           # Maximal kinetic energy cut-off, in Hartree

# Definition of the k-point grid
    ngkpt   8  8  8
  nshiftk   1              # Use one copy of grid only (default)
   shiftk   0.0 0.0 0.0

# Definition of the SCF procedure
    nstep   100        # Maximal number of SCF cycles
   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.

pseudos "C.psp8"