The b3 structure is the zinc blende structure. 
It has a face-centered cubic Bravais lattice and two atoms per cell. 
When one atom is in the origin, the other is at (1/4,1/4,1/4) in 
cartesian coordinates and units of alat.

The reference directory contains the following files:

asy_tmp.asy :  Plot of the Brillouin zone and of the structure

output_keconv.ps: plot of the convergence of the total energy with the
                  kinetic energy cut-off.

output_mur.ps: a plot of the energy as a function of the volume at T=0
               and a Murnaghan fit. Pressure as a function of volume.

output_bands.ps : plot of the band structure.

output_disp.ps.g1 : a plot of the phonon dispersions.

output_grun.ps : plot of the mode Gruneisen parameters.

output_anhar.ps : plot of the anharmonic properties.

sic.elastic.out : the output of the elastic constant calculation.
                  See the end of the file for the elastic constant values.

sic_ph.exp : experimental phonon frequencies.

sic_anhar.exp : experimental thermal expansion.
