Symmetry classification of energy bands in graphene
  We present the results of the first principle calculations of the energy bands in graphene and their symmetry classification. The valence bands and four lowest conduction bands are classified according to their symmetry at the points $\Gamma$ and $K$. Merging of the bands is interpreted in the framework of the group theory. 
E. Kogan and V. U. Nazarov
cond-mat.mes-hall