Keywords: metallic nanocontacts, metallic nanowires, conductance histograms, molecular dynamics, simulation, embedded atom method, EAM, nanotechnology
Molecular dynamics simulations of breaking metallic nanowires
In the present work, we have reviewed the importance of conductance histograms as an experimental tool able to address the statistical behaviour of the electronic transport through metallic nanowires. We have described how molecular dynamics techniques combined with embedded-atom method (EAM) are able to reproduce the general features noticed during metallic nanowire breaking experiments. We have studied the effect of temperature on the minimum cross-section histograms. Our results show that the breaking dynamics is strongly temperature dependent, giving rise to remarkable changes in the computed histograms. We found, for Gold, that conductance and configuration histograms are not correlated, thus indicating that experimental conductance peaks are due to actual quantized conductance effects. For Aluminium, the situation is different, since we found a strong correspondence between our minimum cross-section histograms and the experimental conductance histograms, indicating the relevant role of atomic configurations. We have addressed the study of the stretching of thick Au and Al nanocontacts, finding that there is evidence of the formation of preferred atomic configurations. The electronic origin of such stable atomic arrangements has been discarded, and a plausible explanation has been given in terms of the completion of ionic shells or subshells. Gold and Aluminium nanowires present at room temperature a similar character to that found for alkali wires at low temperatures.