Reduction of activation energy barrier of Stone-Wales transformation in endohedral metallofullerenes

Abstract

Using ab initio calculations, we examine effects of encapsulated metal atoms inside a C60 molecule on the activation energy barrier for the Stone-Wales transformation. The encapsulated metal atoms we study are K, Ca, and La which nominally donate one, two, and three electrons to the C60 cage, respectively. We find that isomerization of the endohedral metallofullerene via the Stone-Wales transformation can occur more easily than that of the empty fullerene owing to the charge transfer. When K, Ca, and La atoms are encapsulated inside the fullerene, the activation energy barriers are lowered by 0.30, 0.55, and 0.80 eV, respectively compared with that of empty C60 (7.16 eV). The lower activation energy barrier of the Stone-Wales transformation implies the higher probability of isomerization and coalescence of metallofullerenes, which require a series of Stone-Wales transformations. © 2006 The American Physical Society.