On the relaxation and stability of 1st and 2nd adlayer 2D Cu islands on the Cu(1 1 1) surface

We present molecular dynamics simulation results concerning the relaxation and the stability of 1st and 2nd adlayer 2D Cu islands deposited on the Cu(1 1 1) surface. We found that, depending on island’s size, the 1st adlayer atoms are contracted, while the surface atoms adjacent to the island edges exhibit small expansion that becomes more important upon deposition of 2nd adlayer islands. In addition, we found that the 1st adlayer exhibits non-uniform deformation, which appears to be related with the stability of the 2nd adlayer islands that are subject to tensile stress, which is more important when they are not stable. It is worth noting that stable 2nd adlayer islands decay when found near the 1st adlayer edges, while the interlayer diffusion between the adlayers increases with the 2nd adlayer size. The results can be used for the interpretation of phenomena related to island decay and stability, such as growth mode switching.