The effective colloid interaction in the Asakura-Oosawa model. Assessment of non-pairwise terms from the virial expansion

TL;DR

This paper evaluates the significance of three- and four-body interactions in the Asakura-Oosawa model by comparing virial coefficients, highlighting their importance at large size ratios and polymer concentrations.

Contribution

It introduces a quantitative method to assess non-pairwise interactions in the coarse-grained Asakura-Oosawa model using virial coefficients.

Findings

Non-pairwise interactions are significant at large size ratios.

Virial coefficient comparison quantifies the impact of many-body interactions.

Neglecting these interactions can lead to inaccuracies in the model.

Abstract

The relevance of neglecting three- and four-body interactions in the coarse-grained version of the Asakura-Oosawa model is examined. A mapping between the first few virial coefficients of the binary nonadditive hard-sphere mixture representative of this model and those arising from the coarse-grained (pairwise) depletion potential approximation allows for a quantitative evaluation of the effect of such interactions. This turns out to be especially important for large size ratios and large reservoir polymer packing fractions.