The advancement of experimental techniques in Biochemistry calls for a more accurate description of various phenomena at the molecular level. Numerical simulations are a convenient tool to provide it, but refined model potentials are needed to account for the changes that local conditions impose to the structure and energetics of the liquids. This work presents a discussion on the methods to design and test such models. An application to refine theMCHO(1) water potential shows the usefulness of theabinitioapproach, in which successive refinements are possible. This not only allows for a better description of the liquids, but also improves our understanding of the relevance of the different contributions to the intermolecular interactions.