Structural, electronic and elastic properties of ultra-light diamond-like crystalline allotropes of carbon-functionalized fullerenes C28

The atomic models of [C28 + C4] fullerites based on C28 fullerenes bound by acetylide C2 bridges are offered. Their structural, elastic and electronic properties are predicted by means of the DFTB method and are discussed in comparison with topologically identical C28 allotropes. The calculations show that, due to unique structure of [C28 + C4] crystals, they would be the lightest among all known fullerites, while their bulk moduli will be essentially higher, than those for more dense C28 fullerites. We propose a possible route for the chemical synthesis of these structures composed of sp-, sp2- and sp3-hybridized atoms, which could be more successful, than previous experimental tests on adsorption of C28 from gas-phase.