Theoretical identification of the lowest-energy structure of (SiC)12 heterocluster: Segregation of C and Si in planar and cage structures

The structures and relative stabilities of various plane and cage isomers of (SiC)12 cluster have been systematically computed using density functional theory at the level of BLYP. A number of starting configurations were generated from the low-energy isomers of C24 cluster via replacing 12 C atoms by Si atoms, which are D6h planar structure, and the D6d, D2h, Oh, and D4h symmetrical fullerene cages. The heterofullerene cage obeying six isolated squares rules are not the most preferred structural motif for (SiC)12 cluster. The structural candidates with fully alternating Si-C arrangement are energetically unfavorable. Instead, the (SiC)12 cluster tend to adopt plane, bowl, saddle, and highly distorted cage structures. In all cases, segregation of C atoms is a common feature.