Water-solid interactions determination ways

The equilibrium structure to which a material crystallizes under given conditions of temperature and pressure is completely determined by the interaction forces between its molecules and these, in turn, are determined by the electronic structure of those molecules, as we have seen. Unfortunately it is almost impossible to proceed uniquely in this way from molecules to crystals in any but the very simplest solids, because the interaction forces are not known with sufficient accuracy. We must therefore usually content ourselves with observing that the crystal structure which actually occurs is consistent with what is known of the molecular interactions, and with comparing the value which we can calculate for its cohesive energy with that found from experiment. In the case of ice, determination of the crystal structure has itself posed very difficult problems which have only been answered by reference back to the structure and interaction of the water molecules. 

---