A test of a phenomenological model of size dependent melting in Au nanoparticles

It is well established that the melting point of a material decreases markedly as the system size approaches the nanoscale. However, despite over a century of study, the validity of any model for size dependent melting point depression has not been proven. In this work molecular dynamics simulations and a classical model of pure Au are used to perform a parameter free test of a phenomenological model of nanosphere melting. Consistent with model predictions, the simulations show that a premelted layer forms on the surface of the nanospheres at temperature well below the bulk melting point and the particle completely transforms to the liquid at a well defined instability temperature. The theoretical prediction of the instability temperature agrees very well with the simulation results, provided that the model is modified to include anisotropic surface properties.