Clearly, this partition coefficient is controlled by the excess chemical potentials and the main challenge for theory and simulations is to correctly predict this term. In general, the excess chemical potential includes steric, short-range (Van der Waals) and electrostatic contributions and a Donnan contribution. If the coacervate is charge-balanced, then the Donnan contribution is zero. In such case, the partition coefficient is predominantly controlled by the subtle balance between the electrostatic interactions and steric effects whereas the system-specific short-range interactions further modulate the result.