Theoretical study of carbon double cones
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We have applied first-principles calculations, based on the density functional theory, to investigate the electronic structure of pure and nitrogen (N) and (B) doped carbon (C) cones and double cones in a hourglass shape. The relative number of s p 3 bonds, together with apex rearrangement and growth environment, determine the energetic stability of these structures. The electronic structure calculations revealed that the s p 2/s p 3 ratio defines the gap size for the non doped double cones. For the doped systems it was observed a gap reduction for one specific configuration and that this reduction is associated with the defects interaction. Densities of states (DOS) changes in response to the application of external electric fields were observed, with some double cones becoming metallic. Permanent electric dipole moments, equal to –1.2 eÅ and –2.3 eÅ, were calculated for the B and N doped double cones. The interaction of this electric dipole with the electric field application can be used to tune the electronic properties of these systems.
KeywordsSolid State and Materials