Abstract
Molecular-dynamics calculations on melting and evaporation in a two-dimensional (2D) Lennard-Jones system show a nonuniform particle distribution in the temperature and density intervals where the phase transitions take place. The behavior of the system agrees qualitatively with the behavior of a corresponding 3D system with a liquid-gas critical point and first-order phase transitions. No evidence is found for the two-stage melting behavior which has recently been predicted.