High pressure induced phase transition and superdiffusion in anomalous fluid confined in flexible nanopores

TL;DR

This study uses Molecular Dynamics simulations to explore how high pressure induces phase transitions and superdiffusion in an anomalous fluid confined within flexible nanopores, revealing a first-order transition linked to structural properties.

Contribution

It demonstrates the occurrence of superdiffusion under high pressure in a confined anomalous fluid and links this behavior to structural changes and a first-order phase transition.

Findings

Superdiffusion occurs at high pressure and low temperature.

Superdiffusive regime is strongly related to fluid structural properties.

The superdiffusion to diffusion transition is a first-order phase transition.

Abstract

The behavior of a confined spherical symmetric anomalous fluid under high external pressure was studied with Molecular Dynamics simulations. The fluid is modeled by a ore-softened potential with two characteristic length scales, which in bulk reproduces the dynamical, thermodynamical and structural anomalous behavior observed for water and other anomalous fluids. Our findings show that this system has a superdiffusion regime for sufficient high pressure and low temperature. As well, our results indicate hat this superdiffusive regime is strongly related with the fluid structural properties and the superdiffusion to diffusion transition is a first order phase transition. We show how the simulation time and statistics are important to obtain the correct dynamical behavior of the confined fluid. Our results are discussed in the basis of the two length scales.