This grant supports theoretical research on electrical transport in nanoscale conductors and their associated mechanical properties. A great deal of progress has been made in understanding electrical transport in nanoscale conductors using quantum transport theory, but progress has been much less systematic in understanding the mechanical properties of nanoconductors. This is an intrinsically harder problem, since unlike transport, cohesion is not determined solely by the electrons at the Fermi surface, but depends on the entire Fermi sea of conduction electrons, as well as the valence electrons and nuclei. Ab initio computational techniques are ideal for studying the ultimate limit of atomic-scale conductors, but they provide few clues to the properties of metal wires intermediate in size between one atom and current 100nm technology.
The PI and co-workers have developed a unified description of the cohesive and conducting properties of the cohesive and conducting properties of metallic nanoconductors, based on a nanoscale generalization of the free-electron model (NFEM). This model has proven to be remarkably rich, explaining observed correlations in the tensile force and quantum conductance of gold nanowires, conductance histograms in noble- and alkali-metal contacts, and the quantum suppression of shot noise in atomic-scale gold wires. Perhaps most importantly for technology, the NFEM predicts that electron-shell effects can overcome the surface-tension driven instability in thin wires, suggesting that stable, atomically-thin metal interconnects are possible. Further analyses will be carried out of the lifetime of these metastable structures under thermal fluctuations, of the limitations of nanowire length due to Peierls instability, and of the possibility of stable "superdeformed" nanowires. Novel schemes for nanoscale self-assembly guided by electron waves will also be investigated within this theoretical framework. Finally, several extensions of the NFEM are proposed to treat problems involving interactions, crystal structure, and multivalent atoms.
This research can have a major impact on the future development of electronic components and devices at the nanoscale. The research will be done in collaboration with the group of Hermann Grabert in Freiburg, Germany, who also coordinates the European Research Training Network on nanoscale conductors. A series of lectures on Nanoscience and Nanotechnology will be organized for the public and industry. %%% This grant supports theoretical research on electrical transport in nanoscale conductors and their associated mechanical properties. This research can have a major impact on the future development of electronic components and devices at the nanoscale. The research will be done in collaboration with the group of Hermann Grabert in Freiburg, Germany, who also coordinates the European Research Training Network on nanoscale conductors. A series of lectures on Nanoscience and Nanotechnology will be organized for the public and industry. ***
