Molecular dynamic simulation of amorphous carbon and graphite interface

Abstract

Amorphous carbon/graphite interface is modeled by molecular dynamic simulation using a Tersoff-type potential function with the Brenner parameters for in-plane interaction combined with the pair potential function for the interplanar bonding. The interface is created by compressing the amorphous carbon produced in a separate simulation with perfect crystalline graphite terminated to expose (1120) planes. The planar structure and weak interplanar bonding allow the graphitic planes to deform in order to accommodate the bonds formed at the interface, which is consistent with the HRTEM study of the interface. The simulation indicates that the generated interface mostly consists of nearly sp2 hybridized bonding connecting the two sides. The bonds across the interface when formed are likely to maintain their equilibrium configurations. Due to the large interplanar spacing, many atoms both on the graphite and a-C sides are left unbonded leaving the interface energetically unfavorable with respect to the bulk. These unbonded radicals probably weaken the structural rigidity of the interface providing a fracture path under stress.