Molecular dynamics simulation of atomic intermixing in microclusters

A molecular dynamics simulation was carried out using the two-dimensional Lennard-Jones system to study the mechanism of atomic intermixing in crystalline microclusters consisting of 127, 217, 331 and 469 atoms. The simulation was performed under the NVE constant condition after the temperature was adjusted. The temperature is aimed at0.375ε/kB so that the clusters consist of a soiid-like core region and a region of surface melting. It is found that the collective motion of atoms amplified by the presence of a free surface causes atomic intermixing in the solid-like core region through the creation and motion of a dislocation or a vacancy or by the collective motions themselves. When the size becomes large, the role of dislocations diminishes in comparison with that of vacancies. For clusters with nominal size of 217 or smaller, atomic intermixing results from the collective motions themselves. The rate per atom of atomic intermixing in the solid-like core is found to be three to four orders of magnitude larger than that in the bulk crystal.