A MOLECULAR-DYNAMICS STUDY AND THE ELECTRONIC-PROPERTIES OF AMORPHOUS-CARBON USING THE TERSOFF POTENTIAL

To obtain qualitatively different amorphous carbon networks we carried out molecular dynamics simulations at different mean atomic densities using the Tersoff potential. Differences among the radial distribution functions obtained as well as among the ratio of threefold- and fourfold-coordinated atoms according to the mean densities are discussed. The electronic stability of the models is investigated by means of their total densities of states which are characterized by significant defect bands. These bands are ascribed to the uncorrelated free-atomic p orbitals occurring in the models. The effect may be quantified by a simple pi bonding analysis which estimates the relative number of non-bonding and of bonding and antibonding pi states by calculating the number of unbonded hybrid orbitals and topological pi defects. For a justification, a number of local densities of states are calculated.