Enyashin, A. N. and A. L. Ivanovskii (2008). "Structural, electronic, cohesive, and elastic properties of diamondlike allotropes of crystalline C40." Physical Review B - Condensed Matter and Materials Physics 77(11).

The atomic models of diamondlike allotropes of crystalline C40 hyperdiamond, hyperlonsdaleite and socalled autointercalated hyperdiamond are offered and using the density-functional based tight-binding method their structural, cohesive, elastic, and electronic properties are predicted as well as their theoretical x-ray diffraction spectra are derived. Among these allotropes the autointercalated hyperdiamond C40 has a unique combined type of both covalent and van der Waals bonding and shows the highest density and hardness.