Dirac Material Graphene

Abstract

The paper presents author's view on spin-rooted properties of graphene supported by numerous experimental and calculation evidences. Correlation of odd p z electrons of the honeycomb lattice meets a strict demand "different orbitals for different spins", which leads to spin polarization of electronic states, on the one hand, and generation of an impressive pool of local spins distributed over the lattice, on the other. These features characterize graphene as a peculiar semimetal with Dirac cone spectrum at particular points of Brillouin zone. However, spin-orbit coupling (SOC), though small but available, supplemented by dynamic SOC caused by electron correlation, transforms graphene-semimetal into graphene-topological insulator (TI). The consequent topological non-triviality and local spins are proposed to discuss such peculiar properties of graphene as high temperature ferromagnetism and outstanding chemical behavior. The connection of these new findings with difficulties met at attempting to convert graphene-TI into semiconductor one is discussed.

sp2 Carbon Stable Radicals

“…Even in the latest publication, concerning a seemingly coordinated attitude to the radical properties of small graphene fragments [28], they are considered with an indispensable eye on the DFT. At the same time, remaining in shadow and developing in parallel, the UHF concept of computational graphenics has acquired new evidence of the legitimacy of the approach and the results obtained [29][30][31][32][33][34][35][36][37]. The semi-empirical UHF method has proven to be very effective so that the calculations of, say, fullerene C 60 or C 70 do not take more than ten minutes on an advanced personal computer, while systems of 200-400 atoms can be considered for one-three days.…”