ИСТИНА

The relative stability of diamond and graphite, 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 these allotropes with very different bonding patterns. We derive the relative energies of the allotropes and prove several general statements. Our analysis yields a quasi-degenerate electronic ground state for graphite and diamond at 0 K. Numerical estimates based on it are in a astonishing 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.