A Monte Carlo simulation study of the two-dimensional melting mechanism

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Abstract
We report here a Monte Carlo study of the thermodynamic and structural properties of a two-dimensional system of 2500 particles interacting by a repulsive inverse sixth power potential. Particular effort was made in the melting region, both to identify the defect structures and to ascertain the thermodynamic changes associated with the transition. Significant precursor fluctuations occurred on both the solid and fluid sides, and the unbinding of dislocation pairs was observed on melting. More complex defect patterns, including grain boundary loops, were also generated near melting. The Kosterlitz–Thouless, Halperin–Nelson, and Young dimensionless elastic constant approached the universal value 16π in the solid, and the orientational correlation range tended to diverge in the fluid near freezing. However, we were unable to distinguish between a very weak (ΔV/V≂0.7%) first order and a continuous transition, since both spatial structures and temporal relaxations became exceedingly long.