Evidence for a liquid-solid critical point in a simple monatomic system

摘要

It is commonly believed that the transition line separating a liquid and a solid cannot be interruptedby a critical point. This opinion is based on the traditional symmetry argument that an isotropicliquid cannot be continuously transformed into a crystal with a discrete rotational and translationalsymmetry. We present here a molecular-dynamics simulation of a simple monatomic systemsuggesting the existence of a liquid-solid spinodal terminating at a critical point. We show that, inthe critical region, the isotropic liquid continuously transforms into a phase with a mesoscopic ordersimilar to that of the smectic liquid crystals. We argue that the existence of both the spinodal and thecritical point can be explained by the close structural proximity between the mesophase and thecrystal. This indicates a possibility of finding a similar thermodynamic behavior in gelating colloids,liquid crystals, and polymers.