A structural comparison of models of colloid-polymer mixtures

TL;DR

This study compares different models of colloid-polymer mixtures, showing that the Morse potential closely replicates the full AO model's structure and cluster populations, providing insights into their similarities and differences.

Contribution

It provides a detailed comparison between the one component AO model, the full AO model, and the Morse potential, highlighting their structural similarities and differences.

Findings

Pair structure of full AO model matches Morse and one component AO

Morse fluid's cluster populations are closer to full AO than one component AO

Morse potential effectively captures key features of colloid-polymer mixtures

Abstract

We study the structure of colloidal fluids with reference to colloid-polymer mixtures. We compare the one component description of the Asakura-Oosawa (AO) idealisation of colloid-polymer mixtures with the full two-component model. We also consider the Morse potential, a variable range interaction, for which the ground state clusters are known. Mapping the state points between these systems, we find that the pair structure of the full AO model is equally well described by the Morse potential or the one component AO approach. We employ a recently developed method to identify in the bulk fluid the ground state clusters relevant to the Morse potential. Surprisingly, when we measure the cluster populations, we find that the Morse fluid is significantly closer the full AO fluid than the one component AO description.