From http://www.lsbu.ac.uk/water/models.html, I see that are many models of water that can "explain" one or some properties of water but no model is accurate enough to explain all the properties of water. From what I understand, all models assume classical mechanics interactions (positive-negative charges as for the protons and electrons) with the Coulombian potential and other potentials. It seems that no model takes into account quantum mechanics "effects" like let's say electron tunneling. I know that water molecule has 2 hydrogen atoms and one would expect the quantum effects to be relevant if one had to build a model that can explain the behaviour of water molecules. I wonder why no model (correct me if I'm wrong) deal with quantum effects? Why are all the models "so bad" at describing water in general? They're only "good" or "so so" in very restricted ranges of parameters like temperature, pressure, etc. Would the models be much more accurate if quantum effects would be taken into account? Hmm I had lots of other questions but I forgot them . Thanks for any input.