The reason why the total potential energy is relatively constant at lower water contents is the negative contribution of the Coulomb energies (Figure (f)), which is also evident from the sum of the Lennard-Jones and Coulomb energies (Figure in the Supporting Information). The lower water content enables a stronger interaction between the ions and the charged carboxylate groups, leading to a stronger Coulomb energy. The curves of the Coulomb energies are consistent with the notion that the Coulomb interaction is the driving force behind the compactification of the systems. These interactions are unique in that their strength increases as water content decreases. This phenomenon can be understood as a dilution or shielding effect: as the water content rises, the shielding by water molecules increases, and conversely, it decreases with lower water content. Furthermore, it is pos- sible to establish a link between the Coulomb interaction strength and the acidity of different SOM types, as already assumed in the discussion about the densities. A higher acidity implies a larger number of charged carboxylate groups in the system, which contribute to the Coulomb potential. For example, SOM I (high acidity) has the strongest Coulomb interaction, whereas the opposite is true for SOM II (low acidity).