Relative stabilities of C92IPR fullerenes

The complete set of 86 isolated-pentagon-rule (IPR) isomers of C-92 has bee n described by the SAM1 quantum-chemical method, and their energetics check ed by density functional theory at the B3LYP/6-31G* level. Although the low est-energy cage is not identical in both approaches, it still exhibits D-2 symmetry in both cases. As energetics themselves cannot produce reliable re lative stabilities at high temperatures, entropy terms are also computed an d the relative-stability problem is treated entirely in terms of the Gibbs function. The lowest-energy structure is not the most populated isomer at h igher temperatures - it is replaced by a D-3 structure. Further stability i nterchanges are possible at very high temperatures, when C-3 and C-1 struct ures are also important. There is a partial agreement of the computations w ith available observed data.