# C in diamond structure. 
 ndtset 3
 elph2_imagden 0.1 eV   # Imaginary shift of the denominator of the sum-over-states 
                        # in the perturbation denominator. Usual value is 0.1 eV to reproduce
                        # experimental broadening at 300K. Increasing the value help the 
                        # convergence with respect to the number of q-points. 
 ngkpt 2 2 2            # k-grid should be at least 4x4x4 for diamond to be converged.
 nshiftk 1
 shiftk 0.0 0.0 0.0

# Ground state density
 iscf1    7
 tolvrs1  1.0d-8      # tolvrs 1.0d-18 should be used for converged results

# Non self-consistent calculation with an abritrary q point (here Gamma)
 getden2  1
 iscf2   -2
 nqpt2    1
 qpt2     0.0 0.0 0.0
 nbdbuf2  2
 tolwfr2  1.0d-8       # tolwfr 1.0d-22 should be used for converged results
 
# Computation at Gamma
 getwfk3  1
 getwfq3  2
 nqpt3    1
 qpt3     0.0 0.0 0.0  # Calculation at Gamma
 ieig2rf3 1            # Static eigenvalues corrections using DFPT (Sternheimer)
 smdelta3 1            # Flag required to produce the _EIGI2D used to 
                       # compute the lifetime of electronic levels.
                       # smdelta = 1 ==> Fermi-Dirac smearing.
 nbdbuf3  2            # 2 buffer bands. RF converges much faster.
 rfphon3  1            # Do phonon response
 rfatpol3 1 2          # Treat displacements of all atoms
 rfdir3   1 1 1        # Do all directions 
 tolwfr3  1.0d-8       # tolwfr 1.0d-22 should be used for converged results

# Cell dependant parameters
 acell 3*6.675
 rprim 0 .5 .5 .5 0 .5 .5 .5 0
 nsym 1                # Symmetries are not yet sufficiently tested.
                       # Disable symmetries.        
 natom 2
 typat 1 1
 xred 3*0.0 3*0.25
 nband 12
 ntypat 1
 znucl 6
 diemac 6
 ecut 5               # Underconverged ecut. 
 enunit 2
 nstep 50
 istwfk *1