The models in these systems, where two H4SiO4 molecules are mutually interacting in an aqueous environment, are intended to explore the dimerization reaction, and therefore to investigate energetics of configurations where the local concentration of silica is sufficient to enable encounters between H4SiO4 molecules. This scenario can occur at super-saturation, at the water-mineral interface, or during chance encounters due to diffusion. The results of the calculations show that in the presence of a neighboring H4SiO4, OSAZ, dipolar complexes, as well as farther separated auto-ionization products, H3SiO4 -and H3O + , simultaneously occur with or without the presence of NaCl. This is in contrast with the results of the "dilute" system from the previous section where the occurrence of OSAZ is exclusive of the occurrence of dipolar complex I, and vice versa. Another, and more significant, difference is that in the dilute system, auto-ionization is favored over zwitterion formation, whereas the reverse is true in the vicinity of two silica monomers.