Electronic structures of solids made of C20 clusters

By performing first-principles calculations based on the density functional theory, we have investigated the optimized structures, cohesive energies and electronic properties of crystalline solids made of C20 clusters. A very interesting result is found from the optimized diamond structure made of C20’s, where the dimered C20 clusters, i.e., (C20)2 dimmers, are formed. Such (C20)2 dimers are then condensed by weak van der Waals interaction between them, leading to the formation of a molecular solid. We also found that one-dimensional molecular solid could be formed when C20 clusters are head to head. Results on C20 clusters arranged in the two-dimensional graphene structure and in fcc structure both show that there are significant coalescences of neighboring C20 fullerenes, leading to metallic characters for both the graphene and fcc structures.