# Correction of coarse-graining errors by a two-level method: application to the Asakura-Oosawa model

## TL;DR

This paper introduces a two-level correction method that combines coarse-grained and fine-grained simulations to improve the accuracy of physical property predictions, demonstrated on the AO colloid-polymer model.

## Contribution

The paper presents a novel self-consistent two-level simulation approach to correct coarse-graining errors in physical system models.

## Key findings

- The liquid-vapour critical point is influenced by three-body interactions.
- The method's accuracy depends on the computational effort.
- Three-body interactions are significant in the AO model.

## Abstract

We present a method that exploits self-consistent simulation of coarse-grained and fine-grained models, in order to analyse properties of physical systems. The method uses the coarse-grained model to obtain a first estimate of the quantity of interest, before computing a correction by analysing properties of the fine system. We illustrate the method by applying it to the Asakura-Oosawa (AO) model of colloid-polymer mixtures. We show that the liquid-vapour critical point in that system is affected by three-body interactions which are neglected in the corresponding coarse-grained model. We analyse the size of this effect and the nature of the three-body interactions. We also analyse the accuracy of the method, as a function of the associated computational effort.