SIMULATING DIFFUSION ON SI(001) 2X1 SURFACES USING A MODIFIED INTERATOMIC POTENTIAL

A modified form of the Tersoff empirical interatomic potential for Si is proposed to improve simulation of adatom behaviors on Si surfaces. The modified form of the potential is consistent with local-density-approximation calculations of the surface electronic band structure of Si(001) 2X1. It is demonstrated that the addition of a screened-Morse-potential tail to the bulk Tersoff interaction behavior when tetrahedral coordination is disrupted improves the results significantly. The surface structure is calculated and shown to yield substantial differences with respect to the original potential form. In particular, anomalous abrupt variations in adatom bonding energy are eliminated and the probability of a successful deposition of the adatom on a lattice site is increased.