Non-equilibrium statistical field theory for classical particles: Impact of correlated initial conditions on non-ideal gases

TL;DR

This paper applies non-equilibrium statistical field theory to classical particles to analyze how initial correlations influence the equation of state in non-ideal gases, revealing significant corrections to pressure beyond particle interactions.

Contribution

It extends existing non-equilibrium statistical field theory to include correlated initial conditions, demonstrating their substantial impact on gas equations of state.

Findings

Correlated initial conditions cause pressure corrections an order of magnitude larger than interaction effects.

The approach reproduces the van der Waals equation for uncorrelated initial conditions.

Initial correlations significantly alter the thermodynamic properties of gases.

Abstract

We use the non-equilibrium statistical field theory for classical particles recently developed by Mazenko and Das and Mazenko, together with the free generating functional for particles initially correlated in phase space derived in Bartelmann et al. to study the impact of initial correlations on the equation of state of real gases. We first show that we can reproduce the well known van der Waals equation of state for uncorrelated initial conditions using this approach. We then impose correlated initial conditions and study their qualitative and quantitative effect on the equation of state of a van der Waals gas. The correlations impose a significant correction to the pressure of an ideal gas which is an order of magnitude larger than the correction due to particle interactions.