Two-component Gaussian core model: strong-coupling limit, Bjerrum pairs, and gas-liquid phase transition

TL;DR

This paper investigates the gas-liquid transition in a two-component Gaussian core model, emphasizing the role of correlations and strong coupling, and highlights the theoretical challenges in modeling this transition.

Contribution

It introduces a detailed analysis of the gas-liquid transition driven by correlations in a two-component Gaussian core model, especially in the strong-coupling limit.

Findings

Transition driven by correlations, not just interactions

Extremely low critical temperature in strong-coupling limit

Theoretical modeling presents significant challenges

Abstract

In the present work we investigate a gas-liquid transition in a two-component Gaussian core model, where particles of the same species repel and those of different species attract. Unlike a similar transition in a one-component system with particles having attractive interactions at long separations, and repulsive interactions at short separations, a transition in the two-component system is not driven solely by interactions, but by a specific feature of the interactions, the correlations. This leads to extremely low critical temperature, as correlations are dominant in the strong-coupling limit. By carrying out various approximations based on standard liquid-state methods, we show that a gas-liquid transition of the two-component system posses a challenging theoretical problem.