A molecular dynamics study on the formation of metallofullerene

The growth process of metallofullerene was studied by the use of the molecular dynamics method. Based on density functional theory (DFT) calculations of various forms of small clusters MCn and M-n (M = La, Sc, Ni), multi-body classical potential functions for M-C and M-M interactions were constructed with the Morse term and the Coulomb term as functions of the coordinate number of a metal atom. The clustering process, starting from 500 isolated carbon atoms and 5 metal atoms, was simulated under a controlled temperature condition, T-c = 3000 K. When La atoms were applied, the stable open-cap structure surrounding the La atom resulted in the lanthanum-containing caged cluster. For the Sc-C system, the host carbon clusters were not affected as much as they were in the La-C case, because of the weaker Coulomb interaction. The precursor Sc atom was encapsulated in the host cage at the final stage of the growth process. For the Ni-C system, the precursor clusters were similar to those in Sc-C system, although the Ni atom finally stayed on the face of a large ring of the caged structure.