Configuration-induced rich electronic properties of bilayer graphene

The objective of this paper is to investigate the geometric and electronic properties of shift-dependent bilayer graphene along armchair and zigzag directions using first-principle calculations. The interlayer distance and the total ground state energy gradually decrease and subsequently increase during the stacking configuration sequence: AA - AB - AA′ - AA. Furthermore, there are dramatic changes in which Dirac cones are transformed into parabolic bands or nonvertical Dirac cones, accompanied by a separation of the Dirac cones, creation of an arc-shaped stateless region, distorted energy dispersions, extra low-energy critical points, and splitting of middle-energy states. The density of states (DOS) exhibits many prominent peaks derived from saddle points. All the bilayer systems remain semimetals, with their free carrier densities strongly depending on the stacking configuration. The main features of energy bands and DOS can be used to identify the subangstrom misalignment stackings.