##############################
bulk:
       4 atom model
       a0 = 5.472608 Ang, b0 = 3.869718 Ang,  c0 = 3.869718 A

surf:
       34 atom thin slab model
       a0 = 5.472608 Ang, b0 = 3.869718 Ang

##############################
bulk/band
     plot the bulk bands projcted onto the surface BZ.

surf/band
     plot the bulk bands at the background of surface bands.

