SAFT γ-MIE COARSE-GRAINED FORCEFIELD FOR THE SIMULATION OF ANIONIC SURFACTANTS: PHASE BEHAVIOUR - poster

Matthias Kiesel, George Jackson, Erich A. Müller, Amparo Galindo
Department of Chemical Engineering, Centre for Process Systems Engineering, Institute for Molecular Science and Engineering, Imperial College London, London SW7 2AZ, U.K

In order to describe and predict the phase behaviour of amphiphilic molecules with standard molecular simulation, a balance must be made between an accurate description at the molecular level and computational cost. In previous works, forcefields based on the SAFT γ-Mie equation of state ^1,2,3 have been derived. A major benefit of this top-down approach is the analytical parameterization, which facilitates the inclusion of a wide range of experimental data, delivering increased transferability and representability to the model. In this work, we extend our SAFT γ-Mie forcefield development workflow to develop models for charged species. Strong electrolytes are modelled as Mie segments with central point charges, interacting via a screened coulomb potential. Interactions between electrolytes and a water model² are incorporated in a Mie potential, optimised to reproduce osmotic coefficients. The model can reproduce osmotic coefficients and densities of solvated electrolytes over the concentration and temperature range of interest.

1: Papaioannou et al., J. Chem. Phys. 140, 054107 (2014)
2: Lobanova et al., Mol. Phys., 113:9-10, 1228-1249 (2015)
3: Rahman et al., J. Phys. Chem. B 122, 9161−9177 (2018)