Eur. Phys. J. D 16, 349-352 (2001)
https://doi.org/10.1007/s100530170127

C₇₈ IPR fullerenes: Computed B3LYP/6-31G*//HF/3-21G temperature-dependent relative concentrations

¹ Department of Physical and Macromolecular Chemistry, Charles University, Albertov 6, 128 43 Praha, Czech Republic
² Laboratories of Computational Chemistry & Fullerene Science, Department of Knowledge-Based Information Engineering, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
³ Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan, R.O.C.

Corresponding author: ^a uhlik@sals.natur.cuni.cz

Received: 28 November 2000
Published online: 15 September 2001

Abstract

The five isolated-pentagon-rule (IPR) satisfying isomers of C₇₈, labeled 1-5, or according to symmetry as D₃, , , , and , are computed. The cage geometries are optimized at the ab initio HF level with the standard 3-21G basis set (HF/3-21G). The separation energetics is then computed using the B3LYP density-functional treatment in the standard 6-31G* basis set (B3LYP/6-31G*//HF/3-21G). Harmonic vibrational frequencies are calculated by the SAM1 semiempirical 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 results are converted into relative concentrations for a wide temperature interval. The structure is the most populated throughout while the species is negligible at all temperatures. The agreement between theory and experiment is reasonable, though some aspects are still to be clarified.