EFFECTIVE HAMILTONIAN ANALYSIS OF FLUID CRITICALITY AND APPLICATION TO THE SQUARE-WELL FLUID

The critical behavior of fluids is analyzed in terms of an effective H amiltonian which is obtained by a Hubbard-Schofield transformation tha t maps the fluid Hamiltonian onto a Wilson-Fisher Ising-type Hamiltoni an. Within this approach we find an approximate relation between criti cal temperature and critical density, depending on the parameters of t he interaction potential, and compare it with simulation results. In t he framework of the effective Hamiltonian we examine the critical data for the square-well fluid obtained using thermodynamic-scaling Monte Carlo and discuss the impact of finite-size effects on the Monte Carlo studies of the fluid criticality. (C) 1998 American Institute of Phys ics. [S0021-9606(98)52503-2].