COMPLICATED EXCHANGE-MEDIATED DIFFUSION MECHANISMS IN AND ON A CU(100) SUBSTRATE AT HIGH-TEMPERATURES

We present results obtained from a molecular dynamics study of the behavior of isolated copper atoms placed on a copper substrate. The atomic interactions are modeled by the embedded atom method. At 900 K we find that diffusion frequently proceeds by a two-step exchange-mediated process. In the first step of the process an isolated surface atom enters the Cu(100) substrate creating a strain along a close-packed row. In the second step the strain is relieved by an atom in the strained row returning to the surface of the Cu(100) substrate. The atom which returns to the surface may be several atoms removed from the atom which entered the substrate.