Liquid–vapor asymmetry in pure fluids: A Monte Carlo simulation study

Abstract

Monte Carlo simulations within the grand canonical ensemble are used to obtain the joint distribution of density and energy fluctuations pL(ρ,u) for two model fluids: a decorated lattice gas and a polymer system. In the near critical region the form of pL(ρ,u) is analyzed using a mixed field finite-size-scaling theory that takes account of liquid–vapor asymmetry. Field mixing transformations are performed that map pL(ρ,u) onto the joint distribution of critical scaling operators p̃=(x,y) appropriate to the Ising fixed point. Carrying out this procedure permits a very accurate determination of the critical point parameters. By forming various projections of p̃=(x,y), the full universal finite-size spectrum of the critical density and energy distributions of fluids is also obtained. In the sub-critical coexistence region, an examination is made of the influence of field mixing on the asymmetry of the density distribution.