This example illustrates how to use the phonon code to calculate
the dispersions along some line or in a plane in the BZ, when it
is not possible to use the Fourier interpolation or when one
wants to check the Fourier interpolation itself.

The calculation proceeds as follows 

1) make a self-consistent calculation for fcc-Al. 
   (input=al.scf.in, output=al.scf.out) 

2) make the phonon calculation for a grid of 444 q-points and interpolates
   the frequencies as in example02.

3) make the phonon calculation along some lines of the BZ and compare
   the results with the interpolated frequencies.
   The output can be seen in al.dispersion.ps (the Fourier interpolated
   frequencies are plotted with a continous line, while the frequencies
   calculated by ph.x are indicated by points). 
