V. G. Bamburov

Stability and structural, elastic, and electronic properties of 3D-(sp 3) carbon allotropes according to DFTB calculations

1 The propensity of carbon atoms to form sp3, sp2, and sp1 hybrid bonds is responsible for the existence of a large number of its allotropic forms. In addition to the known natural carbon allotropes (graphite, diamond, amorphous carbon) and techni cal carbon forms (coke, glassy carbon, carbositall, etc.), a large number of artificial (synthetic) carbon allotropes have been discovered so far. The best studied among them are quasi zero dimensional (0D, fullerenes), quasi one dimensional (1D, nanotubes), and quasi two dimensional (2D, graphene) carbon allotropes (see reviews [1–7]). The number of papers where the synthesis (or prediction) of new carbon allo tropes and their properties are reported is continu ously increasing. According to Hirsch [7], we are entering an era of carbon allotropes. In addition to the mentioned 0D–2D allotropes formed by sp1 or sp2 carbon atoms, crystalline 3D(sp3) carbon forms have attracted much attention (see [2, 8]); among these forms, diamond is the best known allotrope. In the present paper, we report the results of the first systematic study of trends in the stability, struc tural parameters, bulk moduli, and electronic struc ture of five possible crystalline 3D(sp3) carbon allot ropes containing С4 rings and/or С8 cubes by the den sity functional tight binding (DFTB [9–11]) method.