  Surface melting temperature is well-known significantly lower than the bulk
melting point. But we find that the interior melting temperature in ultrathin
nanowires is lower than that of the surface melting . The thermal stability of
helical multi-walled cylindrical gold nanowires is studied using molecular
dynamics simulations. The melting temperature of gold nanowires is lower than
the bulk value, but higher than that of gold nanoclusters. An interesting
interior melting is revealed in the gold nanowires and the thermodynamics is
closely related to interior structures. The melting starts from the interior
atoms, while the surface melting occurs at relatively higher temperature. We
propose that the surface melting represents the overall melting in ultrathin
metallic nanowires.
