Escalona et al. studied Leonardite (HA) models from the VSOMM2 using atomistic simulations, and calculated the solvation free energy of water molecules for different water contents in the Leonardite (HA) systems. They observed that the solvation energy increased until x water = 0.17, when the system reached a fully hydrated state. The free energy remained constant at the free energy of inserting a single water molecule into bulk water until it increased again when it reached x water = 0.43. This indicated that a phase separation between HS molecules and water had begun.