COMPUTER-SIMULATION OF CRITICAL PHENOMENA IN FLUIDS

We extend to the computer simulation of off-lattice models a phenomenological description of finite-size effects, already successfully used in the simulation of lattice systems. The density fluctuations are studied in subsystems of the simulation cell in the canonical ensemble. The density distribution functions of the subsystems are analysed by using finite-size scaling. Results are presented for the two-dimensional Lennard-Jones fluid with N = 4096 particles. The study of the reduced fourth-order cumulants of the density distribution functions allows us to obtain the critical temperature and density. We compare the results with previous values obtained by different methods. We show that finite-size scaling concepts can be extended to off-lattice models. A much larger computer effort would be necessary, however, in order to get reliable estimates of critical exponents and amplitudes.