Using molecular dynamic simulations we study a waterlike model confined between two fixed hydrophobic plates. The system is tested for density, diffusion and structural anomalous behavior and compared with the bulk results. Within the range of confining distances we had explored we observe that in the pressure-temperature phase diagram the temperature of maximum density In the case of three layers the central layer stays liquid while the contact layers crystallize. This result is in agreement with simulations for atomistic models.
Molecular dynamic simulations were employed to study a water-like model confined between hydrophobic and hydrophilic plates. The phase behavior of this system is obtained for different distances between the plates and particle-plate potentials. For both hydrophobic and hydrophilic walls there are the formation of layers. Crystallization occurs at lower temperature at the contact layer than at the middle layer. In addition, the melting temperature decreases as the plates become more hydrophobic. Similarly, the temperatures of maximum density and extremum diffusivity decrease with hydrophobicity.
We explore by molecular dynamic simulations the thermodynamical behavior of an anomalous fluid confined inside rigid and flexible nanopores. The fluid is modeled by a two length scale potential. In the bulk this system exhibits the density and diffusion anomalous behavior observed in liquid water. We show that the anomalous fluid confined inside rigid and flexible nanopores forms
Molecular dynamics simulations were used to study the structural and dynamical properties of a water-like core-softened fluid under confinement when the confining media is rigid or fluctuating. The fluid is modeled using a two-length scale potential that reproduces, in the bulk, the anomalous behavior observed in water. We perform simulations in the NVT ensemble for fixed flat walls and in the NpT ensemble using a fluctuating wall control of pressure to study how the fluid behavior is affected by fixed and non-fixed walls. Our results indicate that the dynamical and structural properties of the fluid are strongly affected by the wall mobility.
We explore the structural properties of anomalous fluids confined in a nanopore using molecular dynamics simulations. The fluid is modeled by core-softened (CS) potentials that have a repulsive shoulder and an attractive well at a further distance. Changing the attractive well depth of the fluid-fluid interaction potential, we studied the behavior of the anomalies in the translational order parameter t and excess entropy s(2) for the particles near to the nanopore wall (contact layer) for systems with two or three layers of particles. When the attractive well of the CS potential is shallow, the systems present a three to two layers transition and, additionally to the usual structural anomaly, a new anomalous region in t and s(2). For attractive well deep enough, the systems change from three layers to a bulk-like profile and just one region of anomaly in t and s(2) is observed. Our results are discussed on the basis of the fluid-fluid and fluid-surface interactions.
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