Comparison of classical and tight-binding molecular dynamics for silicon growth

The growth of a reconstructed (100)-silicon crystal during the deposition of 4 ML of 2-eV silicon atoms is studied with special emphasis on the structure of the grown material. Two different molecular-dynamics simulation methods are employed: A classical scheme using the Stillinger-Weber potential, and a density-functional-based tight-binding scheme devised by Frauenheim et al. [Phys. Rev. B 52, 11 492 (1995)]. We monitor the density, pair correlation, bond and dihedral angle distribution, and ring statistics. Clear differences in the structure of the material grown by the two different simulation schemes are observed. They can be traced back to a too large stiffness of the classical potential, which leaves the grown material in a disordered but not truly amorphous state.