Effects of N doping on the electronic properties of a small carbon atomic chain with distinct sp2 terminations: A first-principles study

Carbon nanostructures consisting of corannulene/coronene-like pieces connected by atomic chains and doped with nitrogen atoms have been addressed by carrying out first-principles calculations within the framework of the spin-polarized density functional theory. Our results show that the conformation, charge distributions, and spin states are significantly influenced by the nitrogen incorporation in comparison to these characteristics of similar pure carbon structures. Higher concentration of incorporated nitrogen leads to a smaller highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap and different conductive states near the Fermi level. In turn the different location of the N-incorporation sites allows switching on and off of the pi-electron magnetism in these systems. We found that the rotational deformation of the terminations with respect to the carbon chain depends on the number and the location of the incorporated N atoms. The most stable N-doped structures exhibit a relative rotation of the terminations of approximately 90 degrees. These findings indicate that by controllable N doping one can tune the conducting channel of carbon chains connected to sp(2) terminations; thus obtaining low band-gap nano-units.