As a new probe of the nature of the two-dimensional melting transition, a Monte Carlo study of nearest-neighbor bond-angular susceptibility on various length scales has been performed. This probe has been used to distinguish between a hexatic phase and a two-phase region. We conclude that the melting transition of both the low-density Lennard-Jones potential system and the hard-disk system is first order in these finite simulations. No qualitative difference in behavior between the two systems was observed.

• Received 9 April 1984

DOI:https://doi.org/10.1103/PhysRevB.30.2755