THERMODYNAMICALLY SELF-CONSISTENT THEORY OF STRUCTURE FOR 3-DIMENSIONAL LATTICE GASES

Recently, methods were developed to solve with high accuracy the equat ions that describe a thermodynamically self-consistent theory for the two-body correlation function, and preliminary results were reported f or three-dimensional lattice gases with nearest-neighbor attractive in teraction [R. Dickman and G. Stell, Phys. Rev. Lett. 77, 996 (1996)]. Here we give a detailed description of our methods and of the results, which are found to be remarkably accurate for both the thermodynamics and structure of these systems. In particular, critical temperatures are predicted to within 0.2% of the best estimates from series expansi ons. Although above the critical temperature the theory yields the sam e critical exponents as the spherical model, this asymptotic behavior sets in only in a very narrow region around the critical point, so tha t the apparent exponents and the thermodynamics are well reproduced up to reduced temperatures of around 10(-2). On the coexistence curve, o n the other hand, the exponents are nonspherical, and considerably mor e accurate than the spherical ones. For instance, the exponent beta(co ex) predicted by the theory for the shape of the coexistence curve is beta(coex)=0.35.