BEHAVIOR OF A 2-DIMENSIONAL SOLID NEAR MELTING FOR REPULSIVE PAIR POTENTIALS

The behaviour was studied of the thermodynamic and structural properti es of a two-dimensional solid near melting, for the repulsive Lennard- Jones potential, and long evolution times. While the elastic constant in the solid falls to zero, with there being a noticeable increase in the density of defects, the pressure, the pair correlation function, t he structure factor and the orientational correlation function remain unaltered. These results give a picture not of a stable solid which is becoming softer and softer and finally loses its elasticity at precis ely the melting point, but of an unstable solid that crumbles above th e melting point losing its elasticity as a consequence of the short re pulsive pair potential being unable to keep the large system stable fo r long evolution times.