Atomistic simulation of point defects at low-index surfaces of noble metals

The formation energies and the migration energies of an isolated vacancy and adatom formed on low-index surfaces are calculated with MAEAM for three noble metals Cu, Ag and Au. The results indicate that the formation energies of an isolated vacancy or adatom increase with increasing atom density in the sequence (1 1 0) → (1 0 0) → (1 1 1), and it is more difficult to form an adatom than to form a vacancy at the same surface. For the mobility of an isolated vacancy, the migration energy grows in the sequence (1 0 0) → (1 1 0) → (1 1 1) for each noble metal. However, a much less migration energy is obtained for the migration of an adatom on (1 1 1) surface.