Extended Gibbs ensembles with flow

TL;DR

This paper develops a statistical framework for finite systems with collective flow, applying it to Lennard-Jones simulations, and shows flow significantly influences microstate distributions in expanding systems.

Contribution

It introduces an extended Gibbs ensemble approach incorporating flow effects, providing a novel way to analyze finite unbound systems with collective motion.

Findings

Flow alters microstate distributions in expanding systems.

The approach accurately models Lennard-Jones simulations with flow.

Flow effects are significant at low densities.

Abstract

A statistical treatment of finite unbound systems in the presence of collective motions is presented and applied to a classical Lennard-Jones Hamiltonian, numerically simulated through molecular dynamics. In the ideal gas limit, the flow dynamics can be exactly re-casted into effective time-dependent Lagrange parameters acting on a standard Gibbs ensemble with an extra total energy conservation constraint. Using this same ansatz for the low density freeze-out configurations of an interacting expanding system, we show that the presence of flow can have a sizeable effect on the microstate distribution.