Thermodynamic and dynamic anomalies for a three dimensional isotropic core-softened potential

TL;DR

This study uses molecular dynamics and integral equations to explore thermodynamic and dynamic anomalies in a three-dimensional isotropic core-softened potential, revealing density and diffusivity maxima similar to water despite lack of directionality.

Contribution

It demonstrates that isotropic core-softened potentials can exhibit water-like anomalies, expanding understanding of the origins of such behaviors beyond directional interactions.

Findings

Density has a maximum at a specific temperature at constant pressure.

Diffusion constant shows a maximum and a minimum at different densities.

Anomalies occur despite the potential lacking directional interactions.

Abstract

Using molecular dynamics simulations and integral equations (Rogers-Young, Percus-Yevick and hypernetted chain closures) we investigate the thermodynamic of particles interacting with continuous core-softened intermolecular potential. Dynamic properties are also analyzed by the simulations. We show that, for a chosen shape of the potential, the density, at constant pressure, has a maximum for a certain temperature. The line of temperatures of maximum density (TMD) was determined in the pressure-temperature phase diagram. Similarly the diffusion constant at a constant temperature, $D$, has a maximum at a density $\rho_{max}$ and a minimum at a density $\rho_{min}<\rho_{max}$. In the pressure-temperature phase-diagram the line of extrema in diffusivity is outside of TMD line. Although in this interparticle potential lacks directionality, this is the same behavior observed in SPC/E water.