ИСТИНА

The relative stability of diamond and graphite structure formed by group IV atoms is readdressed from a new perspective. Unlike most theoretical studies done numerically, we use an analytic model to get an insight into fundamental reasons for quasi-degeneracy of carbon allotropes taking these structures featuring very different bonding patterns. We prove several general statements and derive the relative energies of these allotropes. Our analysis yields a quasi-degenerate electronic ground state for graphite and diamond at 0 K. Numerical estimates based on this analysis are in a astonishingly good agreement with experimental data and recent results of numeric modeling, although obtained with a much smaller numerical effort. An extension of this treatment to the allotropes of silicon proves to be very successful as well: specifically, the strong preference of the diamond structure of silicon as well as the instability of the silicon graphene structure (silicene) with respect to the layer corrugation. References [1] I.V. Popov, A.L. Görne, A.L. Tchougréeff, R. Dronskowski. Relative stability of diamond and graphite as seen through bonds and hybridizations. Phys. Chem. Chem. Phys., Submitted. [2] I.V. Popov, V.V. Slavin, A.L. Tchougréeff, R. Dronskowski. Deductive molecular mechanics of 4-valence carbon allotropes. Carbon, Submitted