Can Monte Carlo simulation describe dynamics? A test on Lennard-Jones systems

A new estimation of physical time in Monte Carlo simulations is derived fro m the requirement that the self-diffusion coefficient measured by Monte Car lo and molecular dynamics simulations have the same value. The dynamics of the particles using both simulation methods are compared by measuring veloc ity autocorrelation functions. Simulations of pure Lennard-Jones liquids an d a binary Lennard-Jones solution show that at small time scales the partic le dynamics are different, but at larger time scales they become similar. A s a critical test crystal growth from the melt is simulated using the propo sed time scale. Both for Monte Carlo and molecular dynamics a linear depend ence of the growth rate on undercooling is found and the measured proportio nality constant (the kinetic coefficient) is equal to within 6%, i.e., with in the statistical error of both methods. (C) 1999 American Institute of Ph ysics. [S0021-9606(99)50306-1].