First-principles molecular-dynamics study of carbon clusters

A universal-parameter tight-binding molecular-dynamics technique that correctly treats interactions in nontetrahedral as well as multicoordinated covalent systems is used to obtain equilibrium geometries for carbon clusters of arbitrary size. For N≤10 the ground states are determined to be linear chains for odd N and closed rings for even N. The minimum-energy cyclic structures exhibit symmetry-lowering in-plane distortions rather than being regular polygons. These findings are in complete agreement with available ab initio results. Large clusters of atoms are used to demonstrate the validity of the method to simulate bulklike diamond and single-layer graphitic structures. The well known 2x1 reconstruction for the (001) face is observed for the diamond cluster