Anomalous Melting Scenario of the Two-Dimensional Core-Softened System

Abstract

We consider the phase behavior of two-dimensional ($2D$)system of particles with an isotropic core-softened potential introduced in our previous publications. As one can expect from the qualitative consideration for the three dimensional case, the system demonstrates a reentrant-melting transition at low densities along with waterlike anomalies in the fluid phase near the melting maximum. In contrast with the three dimensional case, in two dimensions melting is a continuous two-stage transition in the low density part of the phase diagram with an intermediate hexatic phase corresponding to the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario. At the same time, at high densities the system melts through one first-order transition. We also show, that the order of the region of anomalous diffusion and the regions of density and structural anomalies are inverted in comparison with the $3D$ case and have silicalike sequence.