Microscopic structure and thermodynamics of a core-softened model fluid from the second-order integral equations theory

TL;DR

This study uses second-order integral equations to analyze the structure and thermodynamics of a core-softened fluid, successfully capturing density anomalies and providing detailed bridge functions.

Contribution

It demonstrates that second-order hypernetted chain approximation effectively describes the structure and density anomalies of a core-softened fluid model.

Findings

Second-order HNC captures density anomalies.

Comparison with computer simulations validates the approach.

Bridge functions are explicitly calculated.

Abstract

We have studied the structure and thermodynamic properties of isotropic three-dimensional core-softened fluid by using the second-order Ornstein-Zernike integral equations completed by the hypernetted chain and Percus-Yevick closures. The radial distribution functions are compared with those from singlet integral equations and with computer simulation data. The limits of the region of density anomaly resulting from different approximate theories are established. The obtained results show that the second-order hypernetted chain approximation can be used to describe both the structure and the density anomaly of this model fluid. Moreover, we present the results of calculations of the bridge functions.