(139f) Simulations Of Symmetric Tricritical Behavior: Finite-Size Scaling

Whereas finite-size scaling techniques are now routinely applied for ordinary vapor-liquid and liquid-liquid critical phenomena and yield highly accurate estimates of critical points and exponents, this is not true for higher-order multi-critical phenomena. In a much broader context, there are several unresolved issues associated with the type of phase diagrams (i.e. macrophase vs. microphase) and the nature of the different phases in systems with competing interactions such as ferrofluids, surfactant solutions, block copolymers, colloid, and protein solutions. Lattice models, albeit artificial, offer advantages over continuum models both for theories and simulations. In this work, we undertake a study of the Restricted Primitive Model on the simple cubic lattice via grand canonical Monte Carlo simulations and finite-size scaling techniques. The objective of the present work is to establish the phase diagram of this model by using finite-size scaling techniques and by exploiting the analogy of this system to an Ising antiferromagnet. We find order-disorder transitions for reduced temperatures T < 0.51, where the ordered structures resemble those of the NaCl crystal. The order-disorder transition is continuous for 0.15