Heptagraphene: Tunable Dirac Cones in a Graphitic Structure.

ABSTRACT: We predict the existence and dynamical stability of heptagraphene, a new graphitic structure formed of rings of 10 carbon atoms bridged by carbene groups yielding seven-membered rings. Despite the rectangular unit cell, the band structure is topologically equivalent to that of strongly distorted graphene. Density-functional-theory calculations demonstrate that heptagraphene has Dirac cones on symmetry lines that are robust against biaxial strain but which open a gap under shear. At high deformation values bond reconstructions lead to different electronic band arrangements in dynamically stable configurations. Within a tight-binding framework this richness of the electronic behavior is identified as a direct consequence of the symmetry breaking within the cell which, unlike other graphitic

SUBMITTER: Lopez-Bezanilla A 

PROVIDER: S-EPMC5020683 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature