Classical trajectory calculations were employed to study oxygenated (100) diamond surfaces. Atomic forces were computed from two types of potential energy functions, a quantum mechanical potential based on the semiempirical PM3 (parametric method number 3) Hamiltonian which was used to describe the central code core of the surface model and an empirically parametrized potential that was developed to extend the size of the model surface. The results indicate that the energetically most favorable structure of an oxygenated surface is a bridge oxygen monolayer. However, due to the effect of entropy, an on-top oxygen monolayer dominates at high temperatures. Surfaces saturated with oxygen molecules were found to be unstable even at room temperature and to convert to the on-top atomic oxygen structures. Reconstruction of the surface from a (1×1) to a (2×1) configuration was observed to take place when half of the CO was removed from the on-top oxygen monolayer.

• Received 27 December 1993

DOI:https://doi.org/10.1103/PhysRevB.49.11374