Statistical field theory for simple fluids: the collective variables representation

TL;DR

This paper introduces an alternative statistical field theory for simple fluids using collective variables, demonstrating its equivalence to a recent Hubbard-Stratonovich approach and deriving analytical expressions for thermodynamic quantities.

Contribution

It presents a new collective variables-based representation of the statistical field theory for simple fluids, showing its equivalence to existing methods and deriving analytical expressions in two-loop approximation.

Findings

Analytical expressions for pressure and free energy derived

Two different theoretical approaches shown to be equivalent

Introduces a new approximation scheme within the theory

Abstract

An alternative representation of an exact statistical field theory for simple fluids, based on the method of collective variables, is presented. The results obtained are examined from the point of another version of theory that was developed recently by performing a Hubbard-Stratonovich transformation of the configurational Boltzmann factor [J.-M. Caillol, Mol. Phys. 101 (2003) 1617]. The analytical expressions for the pressure and the free energy are derived in two-loop approximation for both versions of theory and it is shown that they are indeed equivalent.The results yield a new type approximation within an untested approximation scheme.