The influence hydrogen atom addition has on charge switching during motion of the metal atom in endohedral Ca@C 60 H 4 isomers

Abstract

Density functional theory has been applied in a study of charge transfer between an endohedral calcium atom and the fullerene cage in Ca@C 60 H 4 and [Ca@C 60 H 4 ] + isomers. Previous calculations on Ca@C 60 have shown that the motion of calcium within a fullerene is accompanied by large changes in electron density on the carbon cage. Based on this observation, it has been proposed that a tethered endohedral fullerene might form the bases of a nanoswitch. Through the addition of hydrogen atoms to one hemisphere of the cage it is shown that, when compared with Ca @C 60 , asymmetric and significantly reduced energy barriers can be generated with respect to motion of the calcium atom. It is proposed that hydrogen atom addition to a fullerene might offer a route for creating a bi-stable nanoswitch that can be fine-tuned through the selection of an appropriate isomer and number of atoms attached to the cage of an endohedral fullerene. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’.