text: Use the "Triple Point Cell"\n\nhttp://www.its-90.com/wtpguide.html\n\n----addition--------\n\nAnother possibility might be to run computer simulations based on the Lennard-Jones potential.\n\nhttp://en.wikipedia.org/wiki/Lennard-Jones_potential\n\nI grant you that it could be tricky. It's just an idea.