Dynamical criterion for two-dimensional freezing

The dynamical criterion for freezing of three-dimensional colloidal fluids recently proposed by Lowen, Palberg, and Simon [Phys. Rev. Lett. 70, 1557 (1993)] states that the ratio of the long-time to short-time self-diffusion coefficients has the universal value 0.1 along the fluid freezing line. Based on Brownian dynamics computer simulations of two-dimensional fluids interacting via different inverse-power pair potentials, it is shown that this criterion also holds for two-dimensional freezing. It is thus the only freezing criterion that holds simultaneously in three and two dimensions.