On topological aspects of 2D graphene like materials
  We study the graphene lattice with a curvature effect. The action depicting multilayers of graphene is portrayed in curved spacetime and effective Dirac equation scopes the curvature effect. The magnetic field is responsible for the geometric variations and these changes are identified as topological aspects in graphene. By varying the geometry of the graphene one can create topologically distinct surfaces which could be remarked as torus or sphere. The 2D hexagonal tessellation induces a curvature effect and the tessellation plane is reduced to a 2-torus having genus g=1. 
M. J. I. Khan, M. Kamran, S. Babar
cond-mat.mes-hall