Computational study of relative stabilities of C60(Ih) and C70(D5h) gas-phase clusters

Structures, energetics, vibrations, and thermodynamics of the title species were evaluated within the AM1 semiempirical method. Whereas this method also indicates that C 70 ( D 5 h ) is the more abundant component of an equilibrium gas-phase mixture than the C 60 ( I h ) cluster, the possible effect of pressure on the relative stability of C 60 vs C 70 species was pointed out. A comparison with MMP2 and MNDO results is also made.