Bonding analyses of unconventional carbon allotropes

Utilizing first-principles electronic-structure calculations, we present the chemical-bonding analyses of hypothetical carbon allotropes based on tetrahedral structure motifs such as T-carbon, TY-carbon and T-graphene. While previous publications on these novel allotropes have dealt with ab initio phonon, band structure and DOS calculations, the focus of this work is the partitioning of the band-structure energy in terms of bonding, nonbonding and antibonding contributions. We re-evaluate the chance of making such allotropes by careful bond analyses and compare them to already known equivalents, namely diamond, graphene and the Buckminsterfullerene molecule. A synthetic route is proposed to a new compound, called TY-carbodiimide, that exhibits similar structure and bonding properties as TY-carbon.