Foremost, let us recall the link between chemical potential µ water (P ), fugacity f and fugacity coefficient ϕ for TIP4P water. In Figure , we present the chemical potential of pure TIP4P water µ water (P ) and the chemical potential of perfect gas µ gas (P ). The reference pressure is chosen to be the vapor pressure of water P vap water = 5300 Pa 49 for which chemical potential of water is set to zero. The chemical potential of perfect gas is written as follows: