Atomic configurations of breaking nanocontacts of aluminium and nickel

A statistical study of favourable atomic configurations of aluminium and nickel nanocontacts during their fracture at 4 K and 300 K was performed. Nanowire breaking events are simulated by using molecular dynamics (MD), the atomic interactions being represented by the state-of-the-art embedded atom method (EAM) interatomic potentials, which are able to fit bulk and surface properties with a high degree of accuracy. A complete determination of atomic positions during the contact allows evaluation of the evolution of the minimum-cross section S_m during stretching. By accumulating S _m traces, obtained from many independent fractures of nanowires, minimum cross-section histograms H(S_m) were built. These simulated histograms reveal the presence of preferential geometrical arrangements during the breaking of the nanocontact and allow a direct comparison with experimental conductance histograms. In particular, aluminium histograms show a remarkable agreement between conductance and minimum cross-section peaks. However for Ni, the interpretation of experimental conductance peaks is more difficult due to the presence of magnetic effects and the possible presence of contaminants.