Structural models of amorphous carbon surfaces

Using tight-binding molecular dynamics, we have constructed structural models of amorphous carbon surfaces, by imposing tensile strain on computer generated networks containing 512 carbon atoms until fracture is produced and two surfaces are formed. Different tensile strains are applied along different directions, in order to mimic the effect of preparation conditions. The surfaces generated with different strains from networks with a given bulk atomic density, exhibit similar structures and formation energies differ by a few 0.01 eV/Angstrom(2). Surface roughness increases with the amount of the graphitic component in the bulk sample. The calculated surface thicknesses are consistent with recent experimental data. (C) 1999 American Institute of Physics. [S0003-6951(99)03038-7].