Rational-function approximation for fluids interacting via piece-wise constant potentials

TL;DR

This paper develops a semi-analytical rational-function approximation method to analyze the structural properties of fluids with complex piece-wise constant interaction potentials, validated against simulations and Percus-Yevick solutions.

Contribution

It introduces a novel rational-function approximation approach for fluids with multi-step potentials, extending analytical tools for complex interaction models.

Findings

Accurately predicts structural properties of fluids with piece-wise constant potentials.

Shows good agreement with simulation data.

Provides a computationally efficient alternative to numerical integral equation solutions.

Abstract

The structural properties of fluids whose molecules interact via potentials with a hard-core plus n piece-wise constant sections of different widths and heights are derived using a (semi-analytical) rational-function approximation method. The results are illustrated for the cases of a square-shoulder plus square-well potential and a shifted square-well potential and compared both with simulation data and with those that follow from the (numerical) solutions of the Percus-Yevick integral equation.