Theoretical investigation of polyhedral hydrocarbons (CH)n

In order to understand the stability of polyhedral hydrocarbons with their curvatures, a systematic study was performed on polyhedral hydrocarbons (CH)n (n = 4, 6, 8, 20, 40, 60, 80, 100) by employing combined ab initio Hartree-Fock and density functional theory method. The calculated results demonstrate that energy per C-H unit (En, C-H) in polyhedral hydrocarbons undergoes a decrease and then an increase with their curvatures unexpectedly and C20H20-Ih with curvature satisfying sp3 hybridization is most stable. Structural analysis reveals that the σ-σ interaction, instead of ring strain or pyramidalization of angles dominates the stability of these polyhedral hydrocarbons.