How dimensionality changes the anomalous behavior and melting scenario of a core-softened potential system?

Abstract

We present a computer simulation study of the phase diagram and anomalous behavior of two-dimensional (2D) and three-dimensional (3D) classical particles repelling each other through an isotropic core-softened potential. As in the analogous three-dimensional case, in 2D a reentrant-melting transition occurs upon compression under not too high pressure, along with a spectrum of thermodynamic and dynamic anomalies in the fluid phase. However, in two dimensions the order of the region of anomalous diffusion and the region of structural anomaly is inverted in comparison with the 3D case, where there exists a water-like sequence of anomalies, and has a silica-like sequence. In the low density part of the 2D phase diagram, melting is a continuous two-stage transition, with an intermediate hexatic phase. All available evidence supports the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario for this melting transition. On the other hand, at high density part of the phase diagram one first-order transition takes place.

Effect of a potential softness on the solid-liquid transition in a two-dimensional core-softened potential system

“…The results of 3D simulations [5,9] suggest that a glass transition can occur in this region. It should be noted, that for this system the phase diagrams in 2D and 3D are qualitatively similar [5,74]. They consist in two structures which are close packed in corresponding dimensions: FCC in 3D and triangular in 2D, between which there are some other phases which depend on the parameters of the potential and dimensionality.…”

“…2(b)) the phase diagram is more complex. It was discussed recently [72][73][74] in detail, and here we recall some main points. There is a clear maximum in the melting curve at low densities.…”

“…The system we study in the present simulations is the smooth repulsive shoulder system (SRSS) introduced in our previous publications [5][6][7][8][9][10][72][73][74]:…”

“…This paper extends our previous results to the set of systems which are characterized by the different softness, in order to study the influence of the softness on the melting scenarios. We present a simulation study of phase behavior of the core-softened system, introduced in our previous publications [5][6][7][8][9][10][72][73][74], in two dimensions. The main goal is to compare the phase diagrams of the systems with the potentials of the increasing softness and to reveal the influence of the softness of the potential on the melting scenarios.…”

“…In our recent papers [72][73][74] we presented a computer simulation study of the phase diagram and anomalous behavior of two-dimensional core-softened potential system [5][6][7][8][9][10] with the soft core σ 1 = 1.35 (see Eq. (1)).…”