Lennnard Jones Potential for Mesoscopic System

The liquid-gas phase transition of a Lennard Jones system of $N=500$ particles is studied via Molecular Dynamics simulations. Rather than displaying a positive isothermal compressibility --- as is demanded of stable systems in the thermodynamic limit --- the system develops a ``Van der Waals loop'', namely, a region with negative isothermal compressibility. We use various observables as well as state-of-the-art computer renderings to elucidate the nature of this behavior.