Ab initio MO Studies on Relative Stabilities of Fullerenes C84 and C94

Abstract

Large-scale computations of temperature- dependent relative stabilities for two isomeric fullerene systems C84 and C94 are carried out at semi-empirical and ab initio MO levels. All C84 IPR isomers are fully optimized at HF/6-31G* level and their harmonic vibration frequencies are calculated by the SAM1 method. The computed energies, structural and vibrational data are employed in the construction of isomeric partition functions and evaluation of the relative Gibbs free energies. The similar Gibbs energy treatment is further applied to C94 IPR isomers. Considerable temperature effects on the relative stabilities and behaviors of enthalpy-entropy interplay in two systems are found and thus good agreements with recent experimental observations are achieved.