Complex Phase Behavior of The System of Particles with Smooth Potential with Repulsive Shoulder and Attractive Well

We report a detailed simulation study of the phase behavior of core softened system with attractive well. Different repulsive shoulder widthes and attractive well depthes are considered which allows to monitor the influence of repulsive and attractive forces on the phase diagram of the system. Thermodynamic anomalies in the systems are also studied. It is shown that the diffusion anomaly is stabilized by small attraction.Comment: 11 pages, 13 figure

Silica-Like Sequence of Anomalies in Core-Softened Systems

In this paper we present a simulation study of density, structural and diffusion anomalies in core-softened system introduced in our previous publications. It is well-known, that with appropriate parametrization, core-softened systems are remarkable model liquids that exhibit anomalous properties observed in tetrahedral liquids such as silica and water. It is widely believed that core-softened potentials demonstrate the water-like sequence of anomalies. We show that with increasing the depth of the attractive part of the potential the order of the region of anomalous diffusion and the regions of density and structural anomalies is inverted and have the silica-like sequence. We also show that the slope of the Widom line is negative like in water.Comment: 5 pages, 4 figures. arXiv admin note: text overlap with arXiv:1109.164

Can random pinning change the melting scenario of two-dimensional core-softened potential system?

In experiments the two-dimensional systems are realized mainly on solid substrates which introduce quenched disorder due to some inherent defects. The defects of substrates influence the melting scenario of the systems and have to be taken into account in the interpretation of the experimental results. We present the results of the molecular dynamics simulations of the two dimensional system with the core-softened potential in which a small fraction of the particles is pinned, inducing quenched disorder.The potentials of this type are widely used for the qualitative description of the systems with the water-like anomalies. In our previous publications it was shown that the system demonstrates an anomalous melting scenario: at low densities the system melts through two continuous transition in accordance with the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory with the intermediate hexatic phase, while at high densities the conventional first order melting transition takes place. We find that the well-known disorder-induced widening of the hexatic phase occurs at low densities, while at high density part of the phase diagram random pinning transforms the first-order melting into two transitions: the continuous KTHNY-like solid-hexatic transition and first-order hexatic-isotropic liquid transition.Comment: 5 pages, 4 figure