The stability of monolayer-thick Ag stripes formed on the Ni(110) surface was studied using first-principles calculations. The Ag stripes were found to be the aggregation of one-dimensional (1-D) silver (Ag) clusters along the 110 direction between the Ni(110) rows, and the clusters extended in the 001 direction to form stripes. Due to the large lattice mismatch between the adsorbed Ag and the Ni substrate, 1-D Ag clusters were not stable with more than seven atoms, and the edge atoms at the 1-D clusters tended to dissociate. The diffusion barriers for the dissociation of the 1-D Ag cluster edges were evaluated using the nudged elastic band method and found to be 0.41 eV for a two-Ag atom cluster (n = 2) and 0.14 eV for a ten-Ag atom cluster (n = 10). Considering surface relaxation of the substrate Ni atoms in the ⟨001⟩ directions, the diffusion barrier further decreased by ∼0.06 eV, which explains the experimental scanning tunneling microscopy images. It was also found that 1-D Ag clusters aggregated to form stripes extending in the 001 direction due to the effect of substrate strain and the one dimensional band formation of Ag 5s-derived states in the stripe direction.
Mizuhara et al. (Wed,) studied this question.