Bond-order potential for transition metal carbide cluster for the growth simulation of a single-walled carbon nanotube

Yasushi Shibuta*, Shigeo Maruyama Department of Materials Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Department of Mechanical Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Abstract A classical multi-body potential for transition metal carbide cluster is developed in the form of the bond-order type potential function. The parameter sets between carbon atoms and several transition metal atoms (Fe, Co and Ni) are constructed by fitting binding energies from Density Functional Theory (DFT) calculations. Using the potential function, clustering process of carbon atoms to a small metal cluster is studied by classical molecular dynamics (MD) simulation. The number of hexagonal rings in the Co cluster increases about twice as fast as in the Fe cluster. This implies that the graphitic lattice interacts more strongly with Co atoms than with Fe atoms. A Co cluster has a crystal structure where metal atoms are regularly allocated and embedded in the hexagonal carbon network in the simulation. In contrast, carbon atoms cover the entire surface in case of the Fe cluster. Additionally, the potential energy surface that a carbon atom feels from FCC metals is examined. The potential energy minima are distributed on the hexagonal network showing the FCC structure can be a template where a graphene is formed.