Figure 4.

(a) Diffusion paths for adatom in the left step corresponding to the ledge between (0001) and ($\overline{1}101$), (b) Minimum energy path of adatom diffusion along the left step by exchanging and hopping mechanisms, (c) Diffusion paths for adatom down the one-layer step between (0001) and ($\overline{1}011$) by hopping (A → C) and exchanging (A → B → C), (d) The change in potential energy corresponding to the two diffusion paths described in (c), (e) Variation of kinetic energy barriers as a function of the step height associated with an adatom diffusion down the left step by exchanging and hopping mechanisms, and (f) Variation of kinetic energy barriers as a function of the step height associated with an adatom diffusion down the right step by exchanging and hopping mechanisms.