First-principles calculations were used to study the stability of C structures with disclinations of angles of ±π/3. Nanocones and saddle-like compounds were investigated. It was shown that a layer with negative disclination was more stable than its converse. An investigation was also made of the effect of introducing B or N, as substitutional impurities, into C nanosaddles. The N, out and on the defect, was shown to increase the formation energy while B, on a heptagon, lowered the formation energy of the heptagonal defect. It was also found that such structures exhibited spin polarization.

Stability of Disclinations in Carbon Monolayer. S.Azevedo: Physics Letters A, 2005, 337[4-6], 431-4