New version of the fluctuation Hamiltonian for liquids near the critical point

TL;DR

This paper introduces a new canonical form of the fluctuational Hamiltonian for liquids near the critical point, incorporating two fluctuating fields and asymmetric coupling based on the $D_5$ catastrophe.

Contribution

It presents a novel canonical form of the fluctuational Hamiltonian that accounts for two fluctuating fields and their asymmetric coupling near the critical point.

Findings

The new Hamiltonian form includes two fluctuating fields: density and entropy.

It is based on the $D_5$ catastrophe, unlike the standard $A_3$ based approach.

The proposed form naturally incorporates asymmetric coupling between the fields.

Abstract

We propose new canonical form of the fluctuational Hamiltonian which takes into account the fact that in the vicinity of the critical point there are two fluctuating fields. They are the field of the number density and the entropy. The proposed canonical form is based on the $D_5$ catastrophe. In contrast to the standard approach of Landau-Ginzburg Hamiltonian which is based on $A_3$ catastrophe the canonical form proposed for the fluctuational Hamiltonian naturally includes the asymmetric coupling between the fields.