Microscopic difference between gas and liquid

[jostpuur]

I am familiar with Ising model, and the phase transition behavior the interacting "arrows" attached to lattice points exhibit. Now, I'm curious to know if similar theoretical models exist of more concrete examples. For example, what is the microscopic difference between gas and liquid? Can the condensation and vaporization be understood through the use of some renormalization techniques?

 

[JustinLevy]

For example, what is the microscopic difference between gas and liquid? Can the condensation and vaporization be understood through the use of some renormalization techniques?

Unfortunately no, as you can move continuously from liquid to gas (by going around the triple point on the phase diagram). Since there is no transition along this path, it suggests there is no way to distinguish them microscopically... they are just both fluids.

 

[jostpuur]

You probably meant the critical point, and not the triple point?

I see that it is possible to go from gas to liquid smoothly, but on the other hand, it is also possible to go from gas to liquid abruptly, so there must be some clear microscopical difference. This is a kind of thing, where it is frustrating that many sources merely mentions various things, leaving it ambiguous what is really known and what is not known. If it is the case that there is no microscopic theoretical model about the phase change between gas and liquid, it is of course very exciting, because one should consider it as a challenge But I would prefer being more certain about it...

 

[atyy]

The best analogy I've hear is it's like a wall between 2 rooms, but the wall has a gap at the top. Is it 2 rooms or one room?

The renormalization group is applicable to universal behavior near the critical point.