Shell and supershell structures of nanowires: A quantum-mechanical analysis - art. no. 033401

The stability of sodium nanowires is studied by modeling them as infinite u niform jellium cylinders and solving self-consistently for the electronic s tructure. The total energy per unit length oscillates as a function of the wire radius giving a shell structure. The amplitude of the energy oscillati ons attenuates regularly, reflecting a supershell structure. We compare our theoretical results with recent experiments [A. I. Yanson et al., Nature 4 00, 144 (1999); Phys. Rev. Lett. 84, 5832 (2000)] performed by the mechanic ally controllable break junctions (MCB) technique. The comparison clarifies the origin of the observed shell structure and especially the formation of the quantum beats of the supershell structure and supports the conclusions based on an earlier semiclassical model. The comparison is also a quantita tive test for the reliability of the simple stabilized-jellium model as wel l as for the accuracy of the equation used to relate the conductivity and t he area of the narrowest point of the constriction.