  The surface dynamics and thermodynamics of metal nanowires are investigated
in a continuum model. Competition between surface tension and electron-shell
effects leads to a rich stability diagram, with fingers of stability extending
to extremely high temperatures for certain magic conductance values. The
linearized dynamics of the nanowire's surface are investigated, including both
acoustic surface phonons and surface self-diffusion of atoms. On the stability
boundary, the surface exhibits critical fluctuations, and the nanowire becomes
inhomogeneous. Some stability fingers coalesce at higher temperatures, or
exhibit overhangs, leading to reentrant behavior. The nonlinear surface
dynamics of unstable nanowires are also investigated in a single-mode
approximation. We find evidence that some unstable nanowires do not break, but
rather neck down to the next stable radius.
