Critical phenomena in colloid-polymer mixtures: interfacial tension, order parameter, susceptibility and coexistence diameter

TL;DR

This study investigates the critical behavior of a colloid-polymer mixture model using simulations, confirming it aligns with 3D Ising universality class and highlighting subtleties in finite size scaling analysis.

Contribution

It provides detailed simulation results of critical phenomena in the AO model, including interfacial tension and amplitude ratios, and discusses finite size scaling subtleties.

Findings

Interfacial tension vanishes at the critical point with exponent ~1.26

Critical amplitude ratios agree with 3D Ising values

Finite size extrapolation is most consistent when ignoring logarithmic size dependences

Abstract

The critical behavior of a model colloid-polymer mixture, the so-called AO model, is studied using computer simulations and finite size scaling techniques. Investigated are the interfacial tension, the order parameter, the susceptibility and the coexistence diameter. Our results clearly show that the interfacial tension vanishes at the critical point with exponent 2\nu ~ 1.26. This is in good agreement with the 3D Ising exponent. Also calculated are critical amplitude ratios, which are shown to be compatible with the corresponding 3D Ising values. We additionally identify a number of subtleties that are encountered when finite size scaling is applied to the AO model. In particular, we find that the finite size extrapolation of the interfacial tension is most consistent when logarithmic size dependences are ignored. This finding is in agreement with the work of Berg et al.[Phys. Rev. B, V47 P497 (1993)]