NUMBER-DEPENDENCE CONCERNS IN GIBBS-ENSEMBLE MONTE-CARLO

The Gibbs-ensemble Monte Carlo method is a powerful tool for estimatin g the location of the coexistence curves of model fluids. This note po ints out, however, some annoying consequences of the fact that in gene ral there may be different numbers of particles in the two phases simu lated. If so, the shape of the coexistence curve may be quite unphysic al; for example, there will be no critical point. We conclude chat it is only with extreme care in this regard that reliable information on critical parameters or the shapes of coexistence curves may be obtaine d from Gibbs-ensemble computations. (C) 1998 American Institute of Phy sics.