Gas-liquid critical point of the ultrasoft restricted primitive model from analytic theory

TL;DR

This paper develops an analytic theoretical framework to study the gas-liquid critical point in the ultrasoft restricted primitive model of polyelectrolytes, revealing that its critical behavior matches that of models with hard cores.

Contribution

The study derives an effective Hamiltonian for the URPM and analyzes its phase behavior using a one-loop approximation, providing new insights into its criticality.

Findings

Critical behavior in URPM matches that of models with hard cores.

Explicit expressions for Hamiltonian coefficients are obtained.

Phase analysis confirms the nature of the gas-liquid critical point.

Abstract

Gas-liquid criticality in the ultrasoft restricted primitive model (URPM) of polyelectrolytes is studied using the collective variables-based theory. For the model, an effective Hamiltonian is derived and explicit expressions for all the coefficients are found in a one-loop approximation. Based on this Hamiltonian, the phase and critical behaviour is analysed. Our results provide evidence that the nature of the gas-liquid criticality in the URPM is the same as in the restricted primitive model that includes a hard core.