Graphene unique properties arise from the collective
behaviour of electrons. The electrons in graphene are
governed by the Dirac equation. The Dirac fermions in
graphene carry one unit of electric charge and can be
manipulated using electromagnetic fields. Strong
interactions between the electrons and the honeycomb
hexagonal lattice of carbon atoms mean that the
dispersion relation is linear and given by E = vp, v is
called the Fermi-Dirac velocity, p is momentum of a
pseudoelectron with pseudospin. The linear dispersion
relation follows from the tight-binding Hamiltonian where
the Fermi velocity in graphene is only about 300 times
less than the speed of light.