Surface step effects on nanoindentation.

Atomistic simulation is used to examine nanoindentation of a Au(111) crystal both near and far from a surface step. While the load needed to nucleate dislocations decreases significantly when indenting close to the step, the extent of the step's influence is not as great as seen experimentally. This behavior is explained by measuring the contact area from the simulation data. A new metric, the slip vector, shows material slip coinciding with the <112> directions of a lowest unstable stacking fault barrier. The slip vector is used to calculate an atomic critical resolved shear stress, which is shown to be a good dislocation nucleation criterion.