quantum-espresso/PHonon/examples/example18

This example illustrates how to use pw.x and ph.x to calculate phonon
frequencies of LiCoO2 with Hubbard U on Co 3d states. Note, the 
phonon frequencies and other quantities are not converged in this
example.

The calculation proceeds as follows (for the meaning of the cited input
variables see the appropriate INPUT_* file)

1) make a self-consistent calculation (input=LiCoO2.scf.in,
   output=LiCoO2.scf.out)

2) make a phonon calculation for gamma point (input=LiCoO2.phG.in,
   output=LiCoO2.phG.out). Note that outdir and prefix have the same
   values as in the input for scf calculation. Note that the q-point 
   (the Gamma point in this case) is read after the namelist inputph. 
   Dynamical matrix will be saved for further analysis in fildyn (whose
   default name is 'matdyn', here overwritten to LiCoO2.dynG).
   Note that epsil=.true. and the response to an electric field and
   the dielectric constant are also calculated.

   The Gamma point is the ONLY one for which the phonon code can be run
   directly after the scf run (provided save file was defined).
   For all other points in the BZ a non-scf preparatory run is needed,
   as it is shown here for q = (0, 0, 1/4).

3) make a phonon calculation for q = (0, 0, 1/4) (input=LiCoO2.phq.in,
   output=LiCoO2.phq.in). Note that the q-point is read after the namelist 
   &inputph. Dynamical matrices will be saved for further analysis in fildyn
   (whose default name is 'matdyn', here overwritten to LiCoO2.dynq). 
   The fildyn file contains the dynamical matrices for q-points that
   are equivalent by symmetry to the q-point given in input, therefore 
   when calculating phonons in the whole BZ the code needs to be run 
   only on inequivalent points.