Theoretical approaches to the structural properties of the square-shoulder fluid

TL;DR

This paper compares three analytical theories for the structure of square-shoulder fluids against simulation data, finding that the simplified exponential approximation provides the best agreement.

Contribution

It evaluates and compares the performance of three analytical theories in predicting the structural properties of square-shoulder fluids.

Findings

Simplified exponential approximation shows the best agreement with simulations.

All three theories reduce to Percus-Yevick for hard-sphere limit.

Theories are analytical in Laplace space and extend hard-sphere results.

Abstract

A comparison of simulation results with the prediction of the structural properties of square-shoulder fluids is carried out to assess the performance of three theories: Tang--Lu's first-order mean spherical approximation, the simplified exponential approximation of the latter and the rational-function approximation. These three theoretical developments share the characteristic of being analytical in Laplace space and of reducing in the proper limit to the Percus--Yevick result for the hard-sphere fluid. Overall, the best agreement with the simulation data is obtained with the simplified exponential approximation.