Discretization Dependence of Criticality in Model Fluids: a Hard-core Electrolyte

TL;DR

This study uses finite-size scaling analyses of lattice discretization levels in simulations to demonstrate that the critical behavior of a model electrolyte is universal and independent of discretization, confirming Ising-type criticality in the continuum limit.

Contribution

It provides evidence that the critical behavior of the RPM electrolyte is universal and not dependent on lattice discretization, clarifying previous conflicting suggestions.

Findings

Critical behavior is independent of discretization level for $ tsim 4$.

Continuum RPM exhibits Ising-type criticality.

Estimated critical parameters for the continuum RPM: $( c^*, hoc^*) o (0.0493, 0.075)$.

Abstract

Grand canonical simulations at various levels, $\zeta=5$-20, of fine- lattice discretization are reported for the near-critical 1:1 hard-core electrolyte or RPM. With the aid of finite-size scaling analyses it is shown convincingly that, contrary to recent suggestions, the universal critical behavior is independent of $\zeta$ $(\grtsim 4)$; thus the continuum $(\zeta\to\infty)$ RPM exhibits Ising-type (as against classical, SAW, XY, etc.) criticality. A general consideration of lattice discretization provides effective extrapolation of the {\em intrinsically} erratic $\zeta$-dependence, yielding $(\Tc^ {\ast},\rhoc^{\ast})\simeq (0.0493_{3},0.075)$ for the $\zeta=\infty$ RPM.