CHIRALITY EFFECTS UPON STABILITIES OF C-84 SPECIES

Relative stabilities in a set of 24 isolated-pentagon fullerene isomer s of C-84 are studied with respect to their chirality properties. The chirality contribution has to be included in partition functions (base d on the MNDO data) in order to reproduce the observed relative stabil ities. Of the 24 isomers, only two are significantly populated at low temperatures; they interchange their relative stabilities and their eq uimolarity point is considerably increased if the chirality contributi on is neglected. At high temperatures, however, other structures becom e the most populated species. The structural interplay is also reflect ed in the overall heat capacity, which is substantially higher than th at of the global minimum (by about 16 J K-1 mol(-1)), but is not parti cularly sensitive to the chirality. The study shows that the computed potential-energy stability order need not be sufficient for understand ing the observed stabilities of fullerenic structures.